package swarm

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os/exec"
	"strings"
	"time"
)

// Config holds collector configuration.
type Config struct {
	LiteLLMBaseURL string
	LiteLLMAPIKey  string
	HTTPTimeout    time.Duration
}

// dockerPsEntry is the JSON shape from `docker ps --format '{{json .}}'`.
type dockerPsEntry struct {
	ID     string `json:"ID"`
	Names  string `json:"Names"`
	Status string `json:"Status"`
	State  string `json:"State"`
}

// dockerInspectEntry is the minimal shape we need from `docker inspect`.
type dockerInspectEntry struct {
	Name  string `json:"Name"`
	State struct {
		Status    string `json:"Status"`
		Running   bool   `json:"Running"`
		StartedAt string `json:"StartedAt"`
		Health    *struct {
			Status string `json:"Status"`
		} `json:"Health"`
	} `json:"State"`
	Config struct {
		Labels map[string]string `json:"Labels"`
	} `json:"Config"`
}

// CollectAll lists all containers labeled agentmon.monitor=true and collects
// a ServiceSnapshot for each.
func CollectAll(ctx context.Context, cfg Config) ([]ServiceSnapshot, error) {
	// List labeled containers (running + stopped).
	out, err := exec.CommandContext(ctx, "docker", "ps", "-a",
		"--filter", "label=agentmon.monitor=true",
		"--format", "{{json .}}",
	).Output()
	if err != nil {
		return nil, fmt.Errorf("docker ps failed: %w", err)
	}

	var entries []dockerPsEntry
	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
		if line == "" {
			continue
		}
		var e dockerPsEntry
		if err := json.Unmarshal([]byte(line), &e); err != nil {
			continue
		}
		entries = append(entries, e)
	}

	client := &http.Client{Timeout: cfg.HTTPTimeout}
	var snapshots []ServiceSnapshot
	for _, e := range entries {
		snap := collectOne(ctx, e.Names, client, cfg)
		snapshots = append(snapshots, snap)
	}

	return snapshots, nil
}

func collectOne(ctx context.Context, name string, client *http.Client, cfg Config) ServiceSnapshot {
	snap := ServiceSnapshot{
		Name:           name,
		ContainerState: "missing",
		HealthState:    "none",
		Status:         "down",
	}

	// Inspect for detailed state.
	out, err := exec.CommandContext(ctx, "docker", "inspect", "--format", "{{json .}}", name).Output()
	if err != nil {
		return snap
	}

	var detail dockerInspectEntry
	if err := json.Unmarshal(out, &detail); err != nil {
		return snap
	}

	snap.Role = detail.Config.Labels["agentmon.role"]
	snap.ContainerState = detail.State.Status

	if detail.State.Health != nil {
		snap.HealthState = detail.State.Health.Status
	}

	// Calculate uptime if running.
	if detail.State.Running && detail.State.StartedAt != "" {
		if t, err := time.Parse(time.RFC3339Nano, detail.State.StartedAt); err == nil {
			snap.UptimeSec = int64(time.Since(t).Seconds())
		}
	}

	// Role-specific probes.
	switch snap.Role {
	case "llm-proxy":
		collectLLMProxy(ctx, &snap, client, cfg)
	case "search":
		collectHTTPProbe(ctx, &snap, client, "http://localhost:"+detail.Config.Labels["agentmon.port"]+"/")
	case "mcp":
		collectPortProbe(ctx, &snap, detail.Config.Labels["agentmon.port"])
	case "db", "voice", "automation":
		// Docker healthcheck state is sufficient; no HTTP probe.
	}

	snap.Status = deriveStatus(snap)
	return snap
}

func collectLLMProxy(ctx context.Context, snap *ServiceSnapshot, client *http.Client, cfg Config) {
	if snap.Extra == nil {
		snap.Extra = make(map[string]any)
	}

	// Health probe.
	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, cfg.LiteLLMBaseURL+"/health/liveliness", nil)
	resp, err := client.Do(req)
	if err == nil {
		code := resp.StatusCode
		snap.HTTPStatus = &code
		resp.Body.Close()
	}

	// Model count.
	if cfg.LiteLLMAPIKey != "" {
		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, cfg.LiteLLMBaseURL+"/v2/model/info", nil)
		req.Header.Set("Authorization", "Bearer "+cfg.LiteLLMAPIKey)
		resp, err := client.Do(req)
		if err == nil {
			defer resp.Body.Close()
			var result struct {
				Data []struct {
					ModelName string `json:"model_name"`
				} `json:"data"`
			}
			if json.NewDecoder(resp.Body).Decode(&result) == nil {
				snap.Extra["model_count"] = len(result.Data)
			}
		}
	}
}

func collectHTTPProbe(ctx context.Context, snap *ServiceSnapshot, client *http.Client, url string) {
	start := time.Now()
	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	resp, err := client.Do(req)
	if err == nil {
		code := resp.StatusCode
		snap.HTTPStatus = &code
		resp.Body.Close()
		ms := time.Since(start).Milliseconds()
		if snap.Extra == nil {
			snap.Extra = make(map[string]any)
		}
		snap.Extra["response_ms"] = ms
	}
}

func collectPortProbe(ctx context.Context, snap *ServiceSnapshot, port string) {
	if port == "" {
		return
	}
	// Use nc to check TCP reachability.
	err := exec.CommandContext(ctx, "nc", "-z", "-w1", "localhost", port).Run()
	reachable := err == nil
	if snap.Extra == nil {
		snap.Extra = make(map[string]any)
	}
	snap.Extra["port_reachable"] = reachable
}

// deriveStatus computes the overall status from container state + health + probes.
func deriveStatus(snap ServiceSnapshot) string {
	if snap.ContainerState != "running" {
		return "down"
	}
	if snap.HealthState == "unhealthy" {
		return "degraded"
	}
	if snap.HTTPStatus != nil && (*snap.HTTPStatus < 200 || *snap.HTTPStatus >= 400) {
		return "degraded"
	}
	if reachable, ok := snap.Extra["port_reachable"].(bool); ok && !reachable {
		return "degraded"
	}
	return "healthy"
}

// DetectIssues scans a set of snapshots for notable problems.
func DetectIssues(services []ServiceSnapshot) Issues {
	issues := Issues{}
	for _, s := range services {
		switch s.Status {
		case "down":
			issues.ServiceDown = append(issues.ServiceDown, s.Name)
		case "degraded":
			issues.ServiceDegraded = append(issues.ServiceDegraded, s.Name)
		}
		if s.Role == "llm-proxy" {
			if extra := s.Extra; extra != nil {
				if count, ok := extra["cooldown_count"].(int); ok && count > 0 {
					issues.LLMCooldowns = true
				}
			}
		}
	}
	return issues
}