import type { ModelClient, Message, ChatRequest, ChatResponse, ModelToolCall, TokenUsage } from '../../models/types.js';
import type { ModelRouter, ModelTier } from '../../models/router.js';
import type { Session } from '../../session/index.js';
import type { ToolRegistry } from '../../tools/registry.js';
import type { ToolExecutor } from '../../tools/executor.js';
import type { ToolResult } from '../../tools/types.js';
import type { ToolPolicyContext } from '../../tools/policy.js';
import type { Attachment } from '../../channels/types.js';
import type { OutboundAttachmentCollector } from './attachments.js';
import { buildUserMessage } from '../../models/media.js';
import { getElevationWindow } from '../../security/elevation.js';
import { auditLogger } from '../../audit/index.js';
import { AsyncLocalStorage } from 'node:async_hooks';

export interface ToolUseEvent {
  type: 'start' | 'end';
  tool: string;
  args?: unknown;
  result?: ToolResult;
}

export interface ToolInventorySnapshot {
  sessionId: string;
  agent: string;
  provider: string;
  skill: string;
  internalCount: number;
  exposedCount: number;
  internalBrowser: string[];
  exposedBrowser: string[];
}

export interface NativeAgentConfig {
  modelClient: ModelClient | ModelRouter;
  systemPrompt: string;
  session?: Session;
  toolRegistry?: ToolRegistry;
  toolExecutor?: ToolExecutor;
  maxIterations?: number;
  onToolUse?: (event: ToolUseEvent) => void;
  /** Policy context for tool filtering (agent tier, provider). */
  toolPolicyContext?: ToolPolicyContext;
  /** Collector for outbound attachments queued by tools (e.g. media.send). */
  attachmentCollector?: OutboundAttachmentCollector;
  /** Hard timeout for each model request in milliseconds. */
  modelTimeoutMs?: number;
}

// Internal message type for the tool loop — supports both text and structured content blocks.
// This is broader than Message to accommodate Anthropic's tool_use/tool_result block format.
interface LoopMessage {
  role: 'user' | 'assistant';
  content: string | unknown[];
}

interface PseudoToolUse {
  name?: string;
  id?: string;
}

interface ExtractedTextToolCall {
  toolCall: ModelToolCall;
  start: number;
  end: number;
}

const LAST_AUDIO_ATTACHMENT_CONFIG_KEY = 'lastAudioAttachment';

interface AudioToolInput {
  data?: string;
  url?: string;
  mime_type?: string;
}

interface AudioToolArgSummary {
  hasData: boolean;
  hasUrl: boolean;
  mimeType?: string;
}

export interface NativeAgentTurnAudioInput {
  data?: string;
  url?: string;
  mime_type?: string;
}

interface NativeAgentRunContext {
  turnAudioInput?: AudioToolInput;
}

export class NativeAgent {
  private static readonly EMPTY_RESPONSE_FALLBACK =
    'I could not generate a response for that. Please try again.';
  private static readonly DEFAULT_MODEL_TIMEOUT_MS = 120_000;
  private modelClient: ModelClient | ModelRouter;
  private systemPrompt: string;
  private session?: Session;
  private inMemoryHistory: Message[] = [];
  private currentTier: ModelTier = 'default';
  private toolRegistry?: ToolRegistry;
  private toolExecutor?: ToolExecutor;
  private maxIterations: number;
  private onToolUse?: (event: ToolUseEvent) => void;
  private _totalUsage: TokenUsage = { inputTokens: 0, outputTokens: 0 };
  private _callCount: number = 0;
  private _toolPolicyContext?: ToolPolicyContext;
  private _attachmentCollector?: OutboundAttachmentCollector;
  private _thinking: boolean = false;
  private _lastToolFingerprint?: string;
  private _cancelRequested = false;
  private _runInProgress = false;
  private _runAbortController?: AbortController;
  private modelTimeoutMs: number;
  private readonly _runContext = new AsyncLocalStorage<NativeAgentRunContext>();

  constructor(config: NativeAgentConfig) {
    this.modelClient = config.modelClient;
    this.systemPrompt = config.systemPrompt;
    this.session = config.session;
    this.toolRegistry = config.toolRegistry;
    this.toolExecutor = config.toolExecutor;
    this.maxIterations = config.maxIterations ?? 200;
    this.onToolUse = config.onToolUse;
    this._toolPolicyContext = config.toolPolicyContext;
    this._attachmentCollector = config.attachmentCollector;
    this.modelTimeoutMs = Number.isFinite(config.modelTimeoutMs)
      ? Math.max(1, Math.floor(config.modelTimeoutMs as number))
      : NativeAgent.DEFAULT_MODEL_TIMEOUT_MS;
  }

  private get history(): Message[] {
    return this.session?.getHistory() ?? [...this.inMemoryHistory];
  }

  async process(
    userMessage: string,
    attachments?: Attachment[],
    turnAudioInput?: NativeAgentTurnAudioInput,
  ): Promise<string> {
    this._cancelRequested = false;
    this._runAbortController = new AbortController();
    const normalizedTurnAudioInput = this.normalizeTurnAudioInput(turnAudioInput)
      ?? this.extractLatestAudioInputFromAttachments(attachments);
    if ('clearAbort' in this.modelClient && typeof this.modelClient.clearAbort === 'function') {
      this.modelClient.clearAbort();
    }
    this._runInProgress = true;
    return await this._runContext.run({ turnAudioInput: normalizedTurnAudioInput }, async () => {
      // Detect and strip !!think prefix for per-message thinking mode
      try {
        if (userMessage.startsWith('!!think ') || userMessage === '!!think') {
          this._thinking = true;
          userMessage = userMessage.replace(/^!!think\s*/, '').trim() || 'Think about this.';
        } else {
          this._thinking = false;
        }

        const userMsg = buildUserMessage(userMessage, attachments);

        if (this.session) {
          this.session.addMessage(userMsg);
        } else {
          this.inMemoryHistory.push(userMsg);
        }

        // If no tools configured, use the simple single-turn path
        if (!this.toolRegistry || !this.toolExecutor) {
          return await this.singleTurn();
        }

        return await this.toolLoop();
      } catch (error) {
        if (this.isAbortError(error)) {
          const cancelledMsg = 'Operation cancelled by user.';
          this.addToHistory({ role: 'assistant', content: cancelledMsg });
          return cancelledMsg;
        }
        throw error;
      } finally {
        this._runInProgress = false;
        this._cancelRequested = false;
        this._runAbortController = undefined;
      }
    });
  }

  private async singleTurn(): Promise<string> {
    this.throwIfCancelled();

    const request: ChatRequest = {
      messages: this.history,
      system: this.systemPrompt,
      ...(this._thinking ? { thinking: true } : {}),
    };

    const response = await this.chatWithRouter(request);
    this.throwIfCancelled();

    this._totalUsage.inputTokens += response.usage.inputTokens;
    this._totalUsage.outputTokens += response.usage.outputTokens;
    this._callCount++;

    const normalizedContent = this.normalizeAssistantContent(response.content);

    // Prepend thinking content if present
    let finalContent = normalizedContent;
    if (response.thinkingContent) {
      finalContent = `<thinking>\n${response.thinkingContent}\n</thinking>\n\n${normalizedContent}`;
    }

    const assistantMsg: Message = { role: 'assistant', content: normalizedContent };
    this.addToHistory(assistantMsg);

    return finalContent;
  }

  private async toolLoop(): Promise<string> {
    const toolRegistry = this.toolRegistry;
    const toolExecutor = this.toolExecutor;
    if (!toolRegistry || !toolExecutor) {
      throw new Error('Tool loop requires tool registry and executor');
    }
    const tools = toolRegistry.filteredToAnthropicFormat(this._toolPolicyContext);

    // Track whether untrusted content (web/fetched/tool output) has been introduced
    // during this run. Used to harden against prompt injection.
    let untrustedContentSeen = false;

    // Detect tool inventory changes to combat conversational inertia in long sessions.
    // When tools change (e.g. new tools added between restarts), the model's prior messages
    // saying "I can't do that" can override tool definitions. Injecting a system note fixes this.
    const currentFingerprint = tools.map(t => t.name).sort().join(',');
    const hasHistory = this.history.length > 1; // more than just the current user message
    let effectiveSystem = this.systemPrompt;

    if (hasHistory && this._lastToolFingerprint !== currentFingerprint) {
      const toolNames = tools.map(t => t.name).join(', ');
      effectiveSystem += `\n\n[Tool inventory updated — available tools: ${toolNames}. Use these tools directly; do not attempt workarounds for functionality that a tool already provides.]`;
    }
    this._lastToolFingerprint = currentFingerprint;

    // Build the loop messages from existing history.
    // These are the messages sent to the model, including any structured tool blocks.
    const loopMessages: LoopMessage[] = this.history.map(m => ({
      role: m.role,
      content: m.content,
    }));

    // Track consecutive identical tool call fingerprints to detect loops.
    // Local LLMs are especially prone to repeatedly requesting the same tool call.
    let lastFingerprint: string | undefined;
    let consecutiveRepeats = 0;
    const maxConsecutiveRepeats = 3;
    let lastToolResults: string[] = [];

    // Track consecutive calls to the same tool (even with different args).
    // Local models often call the same tool with slight query variations.
    let lastToolName: string | undefined;
    let sameToolStreak = 0;
    const maxSameToolStreak = 4; // nudge after 4 calls to the same tool
    let nudged = false;
    let actionIntentNudged = false;

    for (let iteration = 0; iteration < this.maxIterations; iteration++) {
      try {
        this.throwIfCancelled();

        // Build request — cast loopMessages to Message[] because the underlying
        // model client will pass them through to the API which accepts structured content.
        const request = {
          messages: loopMessages as unknown as Message[],
          system: effectiveSystem,
          tools,
          ...(this._thinking ? { thinking: true } : {}),
        };

        const response = await this.chatWithRouter(request);
        this.throwIfCancelled();

        this._totalUsage.inputTokens += response.usage.inputTokens;
        this._totalUsage.outputTokens += response.usage.outputTokens;
        this._callCount++;

        // Some backends emit tool_use JSON as plain text rather than structured tool metadata.
        // Recover those calls when possible so the loop can continue safely.
        let toolCalls = response.toolCalls ?? [];
        let assistantTextContent = response.content;
        if (toolCalls.length === 0) {
          const extracted = this.extractToolCallsFromText(response.content);
          if (extracted && extracted.toolCalls.length > 0) {
            const executableCalls = extracted.toolCalls.filter(tc => Boolean(toolRegistry.getByApiName(tc.name)));
            if (executableCalls.length > 0) {
              toolCalls = executableCalls;
              assistantTextContent = extracted.remainingText;
            }
          }
        }
        if (toolCalls.length === 0) {
          const recovered = this.extractMalformedShellToolCall(response.content);
          if (recovered && toolRegistry.getByApiName(recovered.toolCall.name)) {
            toolCalls = [recovered.toolCall];
            assistantTextContent = recovered.remainingText;
          }
        }

        const wantsToolUse = toolCalls.length > 0;
        if (!wantsToolUse) {
          const pseudoToolUse = this.extractPseudoToolUse(response.content);
          if (this.shouldNudgeForMissingToolCall(response.content, pseudoToolUse) && !actionIntentNudged) {
            actionIntentNudged = true;
            const normalized = this.normalizeAssistantContent(response.content);
            loopMessages.push({ role: 'assistant', content: normalized });
            loopMessages.push({
              role: 'user',
              content: 'You said you would perform an action now, but no tool call was emitted. If a tool is needed, call it now. If blocked, explain the exact blocker.',
            });
            continue;
          }
          const baseContent = pseudoToolUse
            ? this.buildPseudoToolUseWarning(response.content, pseudoToolUse)
            : this.normalizeAssistantContent(response.content);
          let finalContent = baseContent;
          if (response.thinkingContent) {
            finalContent = `<thinking>\n${response.thinkingContent}\n</thinking>\n\n${baseContent}`;
          }
          const assistantMsg: Message = { role: 'assistant', content: baseContent };
          this.addToHistory(assistantMsg);
          return finalContent;
        }

        // Check for repeated tool calls — build a fingerprint from tool names + args
        const fingerprint = toolCalls
          .map(tc => `${tc.name}:${JSON.stringify(tc.args)}`)
          .sort()
          .join('|');

        if (fingerprint === lastFingerprint) {
          consecutiveRepeats++;
        } else {
          consecutiveRepeats = 1;
          lastFingerprint = fingerprint;
        }

        // Track consecutive calls to the same tool (by name, ignoring args)
        const toolNames = toolCalls.map(tc => tc.name).sort().join(',');
        if (toolNames === lastToolName) {
          sameToolStreak++;
        } else {
          sameToolStreak = 1;
          lastToolName = toolNames;
          nudged = false;
        }

        // Build the assistant message with tool_use content blocks
        const assistantContent: unknown[] = [];
        if (assistantTextContent) {
          assistantContent.push({ type: 'text', text: assistantTextContent });
        }
        for (const tc of toolCalls) {
          assistantContent.push({
            type: 'tool_use',
            id: tc.id,
            name: tc.name,
            input: tc.args,
          });
        }
        loopMessages.push({ role: 'assistant', content: assistantContent });

        // Execute each tool call and collect results
        const toolResultBlocks: unknown[] = [];
        lastToolResults = [];
        for (const tc of toolCalls) {
          this.throwIfCancelled();

          const internalName = toolRegistry.getByApiName(tc.name)?.name ?? tc.name;
          this.onToolUse?.({ type: 'start', tool: internalName, args: tc.args });

          let elevationUntilMs: number | undefined;
          let elevationReason: string | undefined;
          let elevationId: string | undefined;

          if (this.session) {
            const elevation = getElevationWindow({
              get: (key) => this.session!.getConfig(key),
              set: (key, value) => this.session!.setConfig(key, value),
              delete: (key) => this.session!.deleteConfig(key),
            }, {
              auditContext: {
                sessionId: this.session.id,
                channel: this._toolPolicyContext?.channel ?? 'unknown',
                sender: this._toolPolicyContext?.sender ?? 'unknown',
              },
            });
            if (elevation.window) {
              elevationUntilMs = elevation.window.untilMs;
              elevationId = elevation.window.id;
              elevationReason = elevation.window.reason;
            }
          }

          const perCallContext: ToolPolicyContext | undefined = this._toolPolicyContext
            ? {
              ...this._toolPolicyContext,
              untrustedContent: untrustedContentSeen,
              elevatedHostUntilMs: elevationUntilMs,
              elevatedHostReason: elevationReason,
              elevatedHostId: elevationId,
            }
            : undefined;

          const toolArgs = this.normalizeToolArgsForExecution(internalName, tc.args);
          const result = await toolExecutor.execute(internalName, toolArgs, perCallContext, {
            signal: this._runAbortController?.signal,
          });

          this.onToolUse?.({ type: 'end', tool: internalName, result });

          const provenance = (internalName === 'web.fetch' || internalName === 'web.search' || internalName === 'browser.content')
            ? 'fetched_content'
            : 'tool_output';

          if (provenance === 'fetched_content') {
            untrustedContentSeen = true;
          }

          const rawContent = result.success ? result.output : (result.error ?? 'Unknown error');
          const resultContent = `[provenance=${provenance} tool=${internalName} untrusted=${provenance === 'fetched_content' ? 'true' : 'false'}]\n${rawContent}\n[/provenance]`;
          toolResultBlocks.push({
            type: 'tool_result',
            tool_use_id: tc.id,
            content: resultContent,
            is_error: !result.success,
          });
          if (result.success && result.output) {
            lastToolResults.push(result.output);
          }
        }

        // If the same tool has been called too many times, append a nudge
        // telling the model to use what it has. This combats local models
        // that endlessly retry searches with slight query variations.
        let nudgeMessage: string | null = null;
        if (sameToolStreak >= maxSameToolStreak && !nudged) {
          nudged = true;
          nudgeMessage = `You have called this tool ${sameToolStreak} times in a row. You have enough information — do NOT call it again. Summarize what you have found and respond to the user now.`;
        }

        // Add tool results as a user message
        loopMessages.push({ role: 'user', content: toolResultBlocks });
        if (nudgeMessage) {
          loopMessages.push({ role: 'user', content: nudgeMessage });
        }

        // Break out if the model is stuck in a repeated tool call loop
        if (consecutiveRepeats >= maxConsecutiveRepeats) {
          const toolOutput = lastToolResults.length > 0
            ? lastToolResults.join('\n\n')
            : 'No results available.';
          const breakMsg = `Tool loop detected (same tool called ${consecutiveRepeats} times). Returning last results:\n\n${toolOutput}`;
          const assistantMsg: Message = { role: 'assistant', content: breakMsg };
          this.addToHistory(assistantMsg);
          return breakMsg;
        }
      } catch (error) {
        if (this.isAbortError(error)) {
          const cancelledMsg = 'Operation cancelled by user.';
          const assistantMsg: Message = { role: 'assistant', content: cancelledMsg };
          this.addToHistory(assistantMsg);
          return cancelledMsg;
        }

        const errorMsg = `Error in tool loop (iteration ${iteration + 1}): ${error instanceof Error ? error.message : String(error)}`;
        const assistantMsg: Message = { role: 'assistant', content: errorMsg };
        this.addToHistory(assistantMsg);
        return errorMsg;
      }
    }

    // Max iterations reached
    const warningMsg = `Stopped after reaching max iterations (${this.maxIterations}). The task may be incomplete.`;
    const assistantMsg: Message = { role: 'assistant', content: warningMsg };
    this.addToHistory(assistantMsg);
    return warningMsg;
  }

  private shouldNudgeForMissingToolCall(content: string, pseudoToolUse: PseudoToolUse | null): boolean {
    if (!content || pseudoToolUse) {
      return false;
    }

    const normalized = content.toLowerCase();
    const intentRegex = /\b(i(?:'m| am)? going to|i(?:'ll| will)|let me|proceeding(?: now)?|i can(?: now)?)\b/;
    if (!intentRegex.test(normalized)) {
      return false;
    }

    const actionRegex = /\b(create|run|execute|call|use|check|fetch|search|read|write|send|retry|proceed|attempt|apply|delete|update|list)\b/;
    return actionRegex.test(normalized);
  }

  private async chatWithRouter(request: ChatRequest): Promise<ChatResponse> {
    const runSignal = this._runAbortController?.signal;
    const requestSignal = request.signal;
    const signal = runSignal && requestSignal
      ? AbortSignal.any([runSignal, requestSignal])
      : (runSignal ?? requestSignal);

    const requestWithSignal = signal
      ? { ...request, signal }
      : request;

    const requestPromise = 'getClient' in this.modelClient
      ? (this.modelClient as ModelRouter).chat(requestWithSignal, this.currentTier)
      : this.modelClient.chat(requestWithSignal);

    let timer: NodeJS.Timeout | undefined;
    let abortCleanup: (() => void) | undefined;
    const timeoutPromise = new Promise<never>((_, reject) => {
      timer = setTimeout(() => {
        const error = new Error(`Model request timed out after ${this.modelTimeoutMs}ms`);
        error.name = 'TimeoutError';
        reject(error);
      }, this.modelTimeoutMs);
      timer.unref?.();
    });
    const abortPromise = signal
      ? new Promise<never>((_, reject) => {
        if (signal.aborted) {
          const error = new Error('Operation cancelled by user.');
          error.name = 'AbortError';
          reject(error);
          return;
        }
        const onAbort = () => {
          const error = new Error('Operation cancelled by user.');
          error.name = 'AbortError';
          reject(error);
        };
        signal.addEventListener('abort', onAbort, { once: true });
        abortCleanup = () => signal.removeEventListener('abort', onAbort);
      })
      : null;

    try {
      return await Promise.race([requestPromise, timeoutPromise, ...(abortPromise ? [abortPromise] : [])]);
    } finally {
      if (timer) {
        clearTimeout(timer);
      }
      abortCleanup?.();
    }
  }

  private addToHistory(msg: Message): void {
    if (this.session) {
      this.session.addMessage(msg);
    } else {
      this.inMemoryHistory.push(msg);
    }
  }

  reset(): void {
    if (this.session) {
      this.session.clear();
    } else {
      this.inMemoryHistory = [];
    }
    this._lastToolFingerprint = undefined;
    this.resetUsage();
  }

  getUsage(): { inputTokens: number; outputTokens: number; calls: number } {
    return { ...this._totalUsage, calls: this._callCount };
  }

  resetUsage(): void {
    this._totalUsage = { inputTokens: 0, outputTokens: 0 };
    this._callCount = 0;
  }

  getHistory(): Message[] {
    return [...this.history];
  }

  setModelTier(tier: ModelTier): void {
    this.currentTier = tier;
  }

  getModelTier(): ModelTier {
    return this.currentTier;
  }

  setSystemPrompt(prompt: string): void {
    this.systemPrompt = prompt;
  }

  setOnToolUse(callback: ((event: ToolUseEvent) => void) | undefined): void {
    this.onToolUse = callback;
  }

  setToolPolicyContext(context: ToolPolicyContext | undefined): void {
    this._toolPolicyContext = context;
  }

  getToolPolicyContext(): ToolPolicyContext | undefined {
    return this._toolPolicyContext;
  }

  getToolInventorySnapshot(): ToolInventorySnapshot {
    if (!this.toolRegistry) {
      return {
        sessionId: '-',
        agent: '-',
        provider: '-',
        skill: '-',
        internalCount: 0,
        exposedCount: 0,
        internalBrowser: [],
        exposedBrowser: [],
      };
    }

    const internal = this.toolRegistry.filteredList(this._toolPolicyContext).map((tool) => tool.name);
    const exposed = this.toolRegistry.filteredToAnthropicFormat(this._toolPolicyContext).map((tool) => tool.name);
    const context = this._toolPolicyContext;
    return {
      sessionId: context?.sessionId ?? '-',
      agent: context?.agent ?? '-',
      provider: context?.provider ?? '-',
      skill: context?.skillName ?? '-',
      internalCount: internal.length,
      exposedCount: exposed.length,
      internalBrowser: internal.filter((name) => name.startsWith('browser.')),
      exposedBrowser: exposed.filter((name) => name.startsWith('browser_')),
    };
  }

  getAvailableToolNames(): string[] {
    if (!this.toolRegistry) {
      return [];
    }
    return this.toolRegistry
      .filteredList(this._toolPolicyContext)
      .map((tool) => tool.name)
      .sort();
  }

  setAttachmentCollector(collector: OutboundAttachmentCollector | undefined): void {
    this._attachmentCollector = collector;
  }

  getAttachmentCollector(): OutboundAttachmentCollector | undefined {
    return this._attachmentCollector;
  }

  cancel(): void {
    if (this._runInProgress) {
      this._cancelRequested = true;
      this._runAbortController?.abort();
      if ('requestAbort' in this.modelClient && typeof this.modelClient.requestAbort === 'function') {
        this.modelClient.requestAbort();
      }
    }
  }

  isCancellable(): boolean {
    return this._runInProgress;
  }

  private throwIfCancelled(): void {
    if (!this._cancelRequested && !this._runAbortController?.signal.aborted) {
      return;
    }

    const error = new Error('Operation cancelled by user.');
    error.name = 'AbortError';
    throw error;
  }

  private isAbortError(error: unknown): boolean {
    return error instanceof Error && error.name === 'AbortError';
  }

  private normalizeToolArgsForExecution(toolName: string, rawArgs: unknown): unknown {
    if (toolName !== 'audio.transcribe') {
      return rawArgs;
    }
    return this.hydrateAudioTranscribeArgs(rawArgs);
  }

  private hydrateAudioTranscribeArgs(rawArgs: unknown): unknown {
    const args = (rawArgs && typeof rawArgs === 'object')
      ? { ...(rawArgs as Record<string, unknown>) }
      : {};
    const original = this.summarizeAudioToolArgs(args);

    const runTurnAudioInput = this._runContext.getStore()?.turnAudioInput;
    if (runTurnAudioInput) {
      this.applyAudioToolInput(args, runTurnAudioInput);
      this.logAudioArgsRewrite('latest_audio_preferred', 'latest_turn', original, args);
      return args;
    }

    const latestTurnAudio = this.getLatestTurnUserAudioInput();
    if (latestTurnAudio) {
      this.applyAudioToolInput(args, latestTurnAudio);
      this.logAudioArgsRewrite('latest_audio_preferred', 'latest_turn', original, args);
      return args;
    }

    if (this.isCurrentTurnVoiceTranscriptFallback()) {
      const persistedAudio = this.getPersistedAudioInput();
      if (persistedAudio) {
        this.applyAudioToolInput(args, persistedAudio);
        this.logAudioArgsRewrite('voice_turn_fallback', 'persisted', original, args);
        return args;
      }
    }

    const normalizedData = this.normalizeAudioTranscribeDataArg(args.data, args.mime_type);
    const normalizedUrl = this.normalizeAudioTranscribeUrlArg(args.url);
    if (normalizedData) {
      args.data = normalizedData;
      delete args.url;
    } else if (normalizedUrl) {
      args.url = normalizedUrl;
      delete args.data;
    } else {
      delete args.data;
      delete args.url;
    }

    const hasData = typeof args.data === 'string' && args.data.length > 0;
    const hasUrl = typeof args.url === 'string' && args.url.length > 0;
    if (hasData || hasUrl) {
      if (hasData && (typeof args.mime_type !== 'string' || args.mime_type.length === 0)) {
        const latestAudioForMime = this.getLatestUserAudioInput();
        if (latestAudioForMime?.mime_type) {
          args.mime_type = latestAudioForMime.mime_type;
        }
      }
      return args;
    }

    const latestAudio = this.getLatestUserAudioInput();
    if (!latestAudio) {
      return args;
    }
    const persistedAudio = this.getPersistedAudioInput();
    const source: 'history' | 'persisted' = persistedAudio?.data === latestAudio.data
      && persistedAudio?.mime_type === latestAudio.mime_type
      ? 'persisted'
      : 'history';
    this.applyAudioToolInput(args, latestAudio);
    this.logAudioArgsRewrite(original.hasData || original.hasUrl ? 'invalid_model_args' : 'missing_model_args', source, original, args);
    return args;
  }

  private summarizeAudioToolArgs(args: Record<string, unknown>): AudioToolArgSummary {
    const hasData = typeof args.data === 'string' && args.data.length > 0;
    const hasUrl = typeof args.url === 'string' && args.url.length > 0;
    const mimeType = typeof args.mime_type === 'string' && args.mime_type.length > 0
      ? args.mime_type
      : undefined;
    return { hasData, hasUrl, mimeType };
  }

  private applyAudioToolInput(args: Record<string, unknown>, audio: AudioToolInput): void {
    if (audio.data) {
      args.data = audio.data;
      delete args.url;
    } else if (audio.url) {
      args.url = audio.url;
      delete args.data;
    } else {
      delete args.data;
      delete args.url;
    }
    if (audio.mime_type) {
      args.mime_type = audio.mime_type;
    }
  }

  private logAudioArgsRewrite(
    reason: 'latest_audio_preferred' | 'voice_turn_fallback' | 'invalid_model_args' | 'missing_model_args',
    source: 'latest_turn' | 'history' | 'persisted',
    original: AudioToolArgSummary,
    normalizedArgs: Record<string, unknown>,
  ): void {
    const finalMime = typeof normalizedArgs.mime_type === 'string' && normalizedArgs.mime_type.length > 0
      ? normalizedArgs.mime_type
      : undefined;
    auditLogger?.toolArgsRewritten({
      tool_name: 'audio.transcribe',
      session_id: this.session?.id,
      source,
      reason,
      original_has_data: original.hasData,
      original_has_url: original.hasUrl,
      original_mime_type: original.mimeType,
      final_mime_type: finalMime,
    });
  }

  private isCurrentTurnVoiceTranscriptFallback(): boolean {
    for (let i = this.history.length - 1; i >= 0; i--) {
      const msg = this.history[i];
      if (msg.role !== 'user') {
        continue;
      }
      if (typeof msg.content === 'string') {
        return msg.content.includes('[Voice message]:');
      }
      if (!Array.isArray(msg.content)) {
        return false;
      }
      return msg.content.some((part) => (
        part.type === 'text'
        && typeof part.text === 'string'
        && part.text.includes('[Voice message]:')
      ));
    }
    return false;
  }

  private getLatestTurnUserAudioInput(): AudioToolInput | null {
    for (let i = this.history.length - 1; i >= 0; i--) {
      const msg = this.history[i];
      if (msg.role !== 'user') {
        continue;
      }
      if (!Array.isArray(msg.content)) {
        return null;
      }
      for (const part of msg.content) {
        if (part.type !== 'audio') {
          continue;
        }
        const source = part.source;
        if (typeof source.data === 'string' && source.data.length > 0 && typeof source.media_type === 'string' && source.media_type.length > 0) {
          return { data: source.data, mime_type: source.media_type };
        }
      }
      return null;
    }
    return null;
  }

  private normalizeTurnAudioInput(turnAudioInput: NativeAgentTurnAudioInput | undefined): AudioToolInput | undefined {
    if (!turnAudioInput) {
      return undefined;
    }
    const data = typeof turnAudioInput.data === 'string' && turnAudioInput.data.length > 0
      ? turnAudioInput.data
      : undefined;
    const url = typeof turnAudioInput.url === 'string' && turnAudioInput.url.length > 0
      ? turnAudioInput.url
      : undefined;
    const mimeType = typeof turnAudioInput.mime_type === 'string' && turnAudioInput.mime_type.length > 0
      ? turnAudioInput.mime_type
      : undefined;
    if (!data && !url) {
      return undefined;
    }
    return {
      ...(data ? { data } : {}),
      ...(url ? { url } : {}),
      ...(mimeType ? { mime_type: mimeType } : {}),
    };
  }

  private extractLatestAudioInputFromAttachments(attachments?: Attachment[]): AudioToolInput | undefined {
    if (!attachments || attachments.length === 0) {
      return undefined;
    }
    for (let i = attachments.length - 1; i >= 0; i--) {
      const attachment = attachments[i];
      if (!attachment.mimeType.startsWith('audio/')) {
        continue;
      }
      const data = typeof attachment.data === 'string' && attachment.data.length > 0
        ? attachment.data
        : undefined;
      const url = typeof attachment.url === 'string' && attachment.url.length > 0
        ? attachment.url
        : undefined;
      if (!data && !url) {
        continue;
      }
      return {
        ...(data ? { data } : {}),
        ...(url ? { url } : {}),
        mime_type: attachment.mimeType,
      };
    }
    return undefined;
  }

  private normalizeAudioTranscribeDataArg(rawData: unknown, rawMimeType: unknown): string | undefined {
    if (typeof rawData !== 'string') {
      return undefined;
    }
    const compact = rawData.replace(/\s+/g, '');
    if (compact.length === 0) {
      return undefined;
    }
    if (!/^[A-Za-z0-9+/=]+$/.test(compact)) {
      return undefined;
    }
    try {
      const decoded = Buffer.from(compact, 'base64');
      if (decoded.length === 0) {
        return undefined;
      }
      const mimeType = typeof rawMimeType === 'string' ? rawMimeType : undefined;
      if (!this.matchesAudioSignature(decoded, mimeType)) {
        return undefined;
      }
      return compact;
    } catch {
      return undefined;
    }
  }

  private matchesAudioSignature(buffer: Buffer, mimeType?: string): boolean {
    const ascii = (offset: number, value: string): boolean => {
      if (buffer.length < offset + value.length) {
        return false;
      }
      return buffer.subarray(offset, offset + value.length).toString('ascii') === value;
    };

    if (!mimeType) {
      return true;
    }

    switch (mimeType) {
      case 'audio/ogg':
        return ascii(0, 'OggS');
      case 'audio/wav':
        return ascii(0, 'RIFF') && ascii(8, 'WAVE');
      case 'audio/webm':
        return buffer.length >= 4
          && buffer[0] === 0x1A
          && buffer[1] === 0x45
          && buffer[2] === 0xDF
          && buffer[3] === 0xA3;
      case 'audio/mpeg':
      case 'audio/mp3':
        return ascii(0, 'ID3')
          || (buffer.length >= 2 && buffer[0] === 0xFF && (buffer[1] & 0xE0) === 0xE0);
      case 'audio/mp4':
      case 'audio/x-m4a':
        return ascii(4, 'ftyp');
      default:
        return true;
    }
  }

  private normalizeAudioTranscribeUrlArg(rawUrl: unknown): string | undefined {
    if (typeof rawUrl !== 'string') {
      return undefined;
    }
    const trimmed = rawUrl.trim();
    if (trimmed.length === 0) {
      return undefined;
    }
    if (!/^https?:\/\//i.test(trimmed)) {
      return undefined;
    }
    return trimmed;
  }

  private getLatestUserAudioInput(): AudioToolInput | null {
    for (let i = this.history.length - 1; i >= 0; i--) {
      const msg = this.history[i];
      if (msg.role !== 'user' || !Array.isArray(msg.content)) {
        continue;
      }

      for (const part of msg.content) {
        if (part.type !== 'audio') {
          continue;
        }
        const source = part.source;
        if (typeof source.data === 'string' && source.data.length > 0 && typeof source.media_type === 'string' && source.media_type.length > 0) {
          return { data: source.data, mime_type: source.media_type };
        }
      }
    }

    return this.getPersistedAudioInput();
  }

  private getPersistedAudioInput(): AudioToolInput | null {
    const persisted = this.session?.getConfig(LAST_AUDIO_ATTACHMENT_CONFIG_KEY);
    if (!persisted) {
      return null;
    }

    try {
      const parsed = JSON.parse(persisted) as { data?: unknown; url?: unknown; mimeType?: unknown };
      const data = typeof parsed.data === 'string' && parsed.data.length > 0 ? parsed.data : undefined;
      const url = typeof parsed.url === 'string' && parsed.url.length > 0 ? parsed.url : undefined;
      const mimeType = typeof parsed.mimeType === 'string' && parsed.mimeType.length > 0 ? parsed.mimeType : undefined;
      if (!data && !url) {
        return null;
      }
      return {
        ...(data ? { data } : {}),
        ...(url ? { url } : {}),
        ...(mimeType ? { mime_type: mimeType } : {}),
      };
    } catch {
      return null;
    }
  }

  private extractPseudoToolUse(content: string): PseudoToolUse | null {
    if (!content) {
      return null;
    }
    if (!/"type"\s*:\s*"tool_use"/.test(content)) {
      return null;
    }

    const nameMatch = content.match(/"name"\s*:\s*"([^"]+)"/);
    const idMatch = content.match(/"id"\s*:\s*"([^"]+)"/);
    return {
      name: nameMatch?.[1],
      id: idMatch?.[1],
    };
  }

  private extractToolCallsFromText(content: string): { toolCalls: ModelToolCall[]; remainingText: string } | null {
    if (!content || content.indexOf('{') === -1) {
      return null;
    }

    const extracted: ExtractedTextToolCall[] = [];
    for (let i = 0; i < content.length; i++) {
      if (content[i] !== '{') {
        continue;
      }
      const end = this.findJsonObjectEnd(content, i);
      if (end === -1) {
        continue;
      }
      const candidate = content.slice(i, end + 1);
      const parsedCall = this.parseTextToolUse(candidate, extracted.length + 1);
      if (parsedCall) {
        extracted.push({
          toolCall: parsedCall,
          start: i,
          end: end + 1,
        });
      }
      i = end;
    }

    if (extracted.length === 0) {
      return null;
    }

    let remainingText = '';
    let cursor = 0;
    for (const item of extracted) {
      remainingText += content.slice(cursor, item.start);
      cursor = item.end;
    }
    remainingText += content.slice(cursor);
    remainingText = remainingText.trim();

    return {
      toolCalls: extracted.map(e => e.toolCall),
      remainingText,
    };
  }

  private parseTextToolUse(candidate: string, ordinal: number): ModelToolCall | null {
    let parsed: unknown;
    try {
      parsed = JSON.parse(candidate);
    } catch {
      return null;
    }

    if (!parsed || typeof parsed !== 'object') {
      return null;
    }

    const obj = parsed as Record<string, unknown>;
    if (obj.type !== 'tool_use') {
      return null;
    }
    if (typeof obj.name !== 'string' || obj.name.trim().length === 0) {
      return null;
    }

    const id = typeof obj.id === 'string' && obj.id.trim().length > 0
      ? obj.id
      : `text_tool_call_${ordinal}`;

    return {
      id,
      name: obj.name,
      args: obj.input ?? {},
    };
  }

  private extractMalformedShellToolCall(content: string): { toolCall: ModelToolCall; remainingText: string } | null {
    if (!content || !/"type"\s*:\s*"tool_use"/.test(content)) {
      return null;
    }

    const nameMatch = content.match(/"name"\s*:\s*"([^"]+)"/);
    if (!nameMatch?.[1]) {
      return null;
    }
    const name = nameMatch[1];
    const normalized = name.replace(/_/g, '.').toLowerCase();
    if (normalized !== 'shell.exec') {
      return null;
    }

    // Recover malformed shell command payloads where inner quotes are not escaped.
    const commandMatch = content.match(/"command"\s*:\s*"([\s\S]*)"\s*}\s*}/);
    if (!commandMatch?.[1]) {
      return null;
    }

    const command = this.sanitizeRecoveredShellCommand(commandMatch[1]);
    if (!command) {
      return null;
    }

    const idMatch = content.match(/"id"\s*:\s*"([^"]+)"/);
    const id = idMatch?.[1]?.trim().length ? idMatch[1] : 'text_tool_call_recovered_shell';

    return {
      toolCall: {
        id,
        name,
        args: { command },
      },
      remainingText: this.stripFirstToolUseObject(content),
    };
  }

  private sanitizeRecoveredShellCommand(raw: string): string {
    let command = raw.trim();
    if (command.length === 0) {
      return '';
    }

    // Common malformed pattern: opening quote duplicated into value.
    if ((command.startsWith('"') && !command.endsWith('"')) || (command.startsWith('\'') && !command.endsWith('\''))) {
      command = command.slice(1).trimStart();
    }

    return command;
  }

  private stripFirstToolUseObject(content: string): string {
    const typeMatch = /"type"\s*:\s*"tool_use"/.exec(content);
    if (!typeMatch || typeMatch.index < 0) {
      return content.trim();
    }

    const objectStart = content.lastIndexOf('{', typeMatch.index);
    if (objectStart < 0) {
      return content.trim();
    }

    const objectEnd = this.findObjectEndByBraceDepth(content, objectStart);
    if (objectEnd < 0) {
      return content.trim();
    }

    return `${content.slice(0, objectStart)}${content.slice(objectEnd + 1)}`.trim();
  }

  private findObjectEndByBraceDepth(content: string, start: number): number {
    let depth = 0;
    for (let i = start; i < content.length; i++) {
      const ch = content[i];
      if (ch === '{') {
        depth++;
      } else if (ch === '}') {
        depth--;
        if (depth === 0) {
          return i;
        }
      }
    }
    return -1;
  }

  private findJsonObjectEnd(content: string, start: number): number {
    let depth = 0;
    let inString = false;
    let escaping = false;

    for (let i = start; i < content.length; i++) {
      const ch = content[i];

      if (inString) {
        if (escaping) {
          escaping = false;
          continue;
        }
        if (ch === '\\') {
          escaping = true;
          continue;
        }
        if (ch === '"') {
          inString = false;
        }
        continue;
      }

      if (ch === '"') {
        inString = true;
        continue;
      }
      if (ch === '{') {
        depth++;
        continue;
      }
      if (ch === '}') {
        depth--;
        if (depth === 0) {
          return i;
        }
      }
    }

    return -1;
  }

  private buildPseudoToolUseWarning(rawContent: string, pseudo: PseudoToolUse): string {
    const toolName = pseudo.name ?? 'unknown';
    const toolId = pseudo.id ?? 'unknown';
    return [
      'Tool call was emitted as plain text and was not executed.',
      `Tool: ${toolName} (id: ${toolId})`,
      'This usually means the current model/backend did not return structured tool metadata.',
      'Original assistant output:',
      rawContent,
    ].join('\n');
  }

  private normalizeAssistantContent(content: string): string {
    if (content.trim().length > 0) {
      return content;
    }
    return NativeAgent.EMPTY_RESPONSE_FALLBACK;
  }
}