package postgres

import (
	"context"
	"time"
)

type FrameworkStats struct {
	ActiveSessions int `json:"active_sessions"`
	Runs           int `json:"runs"`
	Tools          int `json:"tools"`
	Errors         int `json:"errors"`
}

type Summary struct {
	ActiveSessions int                       `json:"active_sessions"`
	RunsToday      int                       `json:"runs_today"`
	ToolCallsToday int                       `json:"tool_calls_today"`
	ErrorsToday    int                       `json:"errors_today"`
	TokensToday    int64                     `json:"tokens_today"`
	CostToday      float64                   `json:"cost_today"`
	AvgDurationMS  float64                   `json:"avg_duration_ms"`
	ByFramework    map[string]FrameworkStats `json:"by_framework"`
}

type TimeseriesBucket struct {
	TS            time.Time `json:"ts"`
	Runs          int       `json:"runs"`
	Tools         int       `json:"tools"`
	Errors        int       `json:"errors"`
	Tokens        int64     `json:"tokens"`
	InputTokens   int64     `json:"input_tokens"`
	OutputTokens  int64     `json:"output_tokens"`
	Cost          float64   `json:"cost"`
	AvgDurationMS float64   `json:"avg_duration_ms"`
}

type TimeseriesResult struct {
	Window string             `json:"window"`
	Bucket string             `json:"bucket"`
	Series []TimeseriesBucket `json:"series"`
}

func (d *DB) GetSummary(ctx context.Context) (*Summary, error) {
	now := time.Now()
	midnight := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())

	// Active sessions are open sessions with recent activity. Some hook sources can
	// miss session.end, so "started but never ended" alone overstates live work.
	activeQ := `
		WITH session_groups AS (
			SELECT
				session_id,
				COALESCE((ARRAY_AGG(source_framework ORDER BY CASE WHEN type = 'session.start' THEN 0 ELSE 1 END, ts) FILTER (WHERE source_framework IS NOT NULL))[1], 'unknown') AS framework,
				MAX(ts) AS last_event_at,
				BOOL_OR(type = 'session.start') AS has_start,
				BOOL_OR(type = 'session.end') AS has_end
			FROM events
			WHERE session_id IS NOT NULL
			GROUP BY session_id
		)
		SELECT framework, COUNT(*)
		FROM session_groups
		WHERE has_start
		  AND NOT has_end
		  AND last_event_at >= $1
		GROUP BY framework
	`
	activeRows, err := d.sql.QueryContext(ctx, activeQ, now.Add(-15*time.Minute))
	if err != nil {
		return nil, err
	}
	defer activeRows.Close()

	byFramework := make(map[string]FrameworkStats)
	var activeSessions int
	for activeRows.Next() {
		var fw string
		var count int
		if err := activeRows.Scan(&fw, &count); err != nil {
			return nil, err
		}
		fs := byFramework[fw]
		fs.ActiveSessions = count
		byFramework[fw] = fs
		activeSessions += count
	}
	if err := activeRows.Err(); err != nil {
		return nil, err
	}

	// Per-framework aggregates for today
	fwQ := `
		SELECT
			COALESCE(source_framework, 'unknown'),
			COUNT(*) FILTER (WHERE type = 'run.start')        AS runs,
			COUNT(*) FILTER (WHERE type = 'span.end'
			                   AND payload->'attributes'->>'span_kind' = 'tool') AS tools,
			COUNT(*) FILTER (WHERE type = 'error')            AS errors
		FROM events
		WHERE ts >= $1
		  AND type IN ('run.start', 'span.end', 'error')
		GROUP BY source_framework
	`
	rows, err := d.sql.QueryContext(ctx, fwQ, midnight)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var totalRuns, totalTools, totalErrors int

	for rows.Next() {
		var fw string
		var fs FrameworkStats
		if err := rows.Scan(&fw, &fs.Runs, &fs.Tools, &fs.Errors); err != nil {
			return nil, err
		}
		if existing, ok := byFramework[fw]; ok {
			fs.ActiveSessions = existing.ActiveSessions
		}
		byFramework[fw] = fs
		totalRuns += fs.Runs
		totalTools += fs.Tools
		totalErrors += fs.Errors
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	// Usage stats for today (tokens, cost, avg latency)
	usageQ := `
		SELECT
			COALESCE(SUM((payload->'payload'->'usage'->>'total_tokens')::bigint), 0),
			COALESCE(SUM((payload->'payload'->'usage'->>'total_cost')::float8), 0),
			COALESCE(AVG((payload->'payload'->>'duration_ms')::float8), 0)
		FROM events
		WHERE type = 'run.end'
		  AND ts >= $1
	`
	var tokensToday int64
	var costToday, avgDurationMS float64
	if err := d.sql.QueryRowContext(ctx, usageQ, midnight).Scan(&tokensToday, &costToday, &avgDurationMS); err != nil {
		return nil, err
	}

	return &Summary{
		ActiveSessions: activeSessions,
		RunsToday:      totalRuns,
		ToolCallsToday: totalTools,
		ErrorsToday:    totalErrors,
		TokensToday:    tokensToday,
		CostToday:      costToday,
		AvgDurationMS:  avgDurationMS,
		ByFramework:    byFramework,
	}, nil
}

type TopTool struct {
	Name  string `json:"name"`
	Count int    `json:"count"`
}

type TopModel struct {
	Name  string `json:"name"`
	Count int    `json:"count"`
}

func (d *DB) GetTopTools(ctx context.Context, limit int) ([]TopTool, error) {
	if limit <= 0 {
		limit = 10
	}
	now := time.Now()
	midnight := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())

	q := `
		SELECT
			payload->'attributes'->>'name' AS tool_name,
			COUNT(*)                        AS cnt
		FROM events
		WHERE type = 'span.end'
		  AND payload->'attributes'->>'span_kind' = 'tool'
		  AND payload->'attributes'->>'name' IS NOT NULL
		  AND ts >= $1
		GROUP BY tool_name
		ORDER BY cnt DESC
		LIMIT $2
	`
	rows, err := d.sql.QueryContext(ctx, q, midnight, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []TopTool
	for rows.Next() {
		var t TopTool
		if err := rows.Scan(&t.Name, &t.Count); err != nil {
			return nil, err
		}
		out = append(out, t)
	}
	return out, rows.Err()
}

func (d *DB) GetTopModels(ctx context.Context, limit int) ([]TopModel, error) {
	if limit <= 0 {
		limit = 10
	}
	now := time.Now()
	midnight := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())

	q := `
		SELECT
			payload->'payload'->>'model' AS model_name,
			COUNT(*)                     AS cnt
		FROM events
		WHERE type = 'run.end'
		  AND payload->'payload'->>'model' IS NOT NULL
		  AND payload->'payload'->>'model' <> ''
		  AND ts >= $1
		GROUP BY model_name
		ORDER BY cnt DESC
		LIMIT $2
	`
	rows, err := d.sql.QueryContext(ctx, q, midnight, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []TopModel
	for rows.Next() {
		var m TopModel
		if err := rows.Scan(&m.Name, &m.Count); err != nil {
			return nil, err
		}
		out = append(out, m)
	}
	return out, rows.Err()
}

func bucketForWindow(window string) string {
	switch window {
	case "1h":
		return "1 minute"
	case "6h":
		return "5 minutes"
	case "7d":
		return "1 hour"
	default: // "24h"
		return "15 minutes"
	}
}

func durationForWindow(window string) time.Duration {
	switch window {
	case "1h":
		return 1 * time.Hour
	case "6h":
		return 6 * time.Hour
	case "7d":
		return 7 * 24 * time.Hour
	default: // "24h"
		return 24 * time.Hour
	}
}

func bucketLabelForWindow(window string) string {
	switch window {
	case "1h":
		return "1m"
	case "6h":
		return "5m"
	case "7d":
		return "1h"
	default: // "24h"
		return "15m"
	}
}

func (d *DB) GetTimeseries(ctx context.Context, window string) (*TimeseriesResult, error) {
	bucket := bucketForWindow(window)
	dur := durationForWindow(window)
	since := time.Now().Add(-dur)

	q := `
		SELECT
			date_bin($1::interval, ts, '2000-01-01'::timestamptz) AS bucket_ts,
			COUNT(*) FILTER (WHERE type = 'run.start')             AS runs,
			COUNT(*) FILTER (WHERE type = 'span.end'
			                   AND payload->'attributes'->>'span_kind' = 'tool') AS tools,
			COUNT(*) FILTER (WHERE type = 'error')                 AS errors,
			COALESCE(SUM((payload->'payload'->'usage'->>'total_tokens')::bigint)
			         FILTER (WHERE type = 'run.end'), 0)           AS tokens,
			COALESCE(SUM((payload->'payload'->'usage'->>'input_tokens')::bigint)
			         FILTER (WHERE type = 'run.end'), 0)           AS input_tokens,
			COALESCE(SUM((payload->'payload'->'usage'->>'output_tokens')::bigint)
			         FILTER (WHERE type = 'run.end'), 0)           AS output_tokens,
			COALESCE(SUM((payload->'payload'->'usage'->>'total_cost')::float8)
			         FILTER (WHERE type = 'run.end'), 0)           AS cost,
			COALESCE(AVG((payload->'payload'->>'duration_ms')::float8)
			         FILTER (WHERE type = 'run.end'), 0)           AS avg_duration_ms
		FROM events
		WHERE ts >= $2
		  AND type IN ('run.start', 'run.end', 'span.end', 'error')
		GROUP BY bucket_ts
		ORDER BY bucket_ts ASC
	`

	rows, err := d.sql.QueryContext(ctx, q, bucket, since)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var series []TimeseriesBucket
	for rows.Next() {
		var b TimeseriesBucket
		if err := rows.Scan(&b.TS, &b.Runs, &b.Tools, &b.Errors,
			&b.Tokens, &b.InputTokens, &b.OutputTokens, &b.Cost, &b.AvgDurationMS); err != nil {
			return nil, err
		}
		series = append(series, b)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	return &TimeseriesResult{
		Window: window,
		Bucket: bucketLabelForWindow(window),
		Series: series,
	}, nil
}