package api

import (
	"net/http"
	"time"

	"github.com/ez-api/ez-api/internal/model"
	"github.com/ez-api/ez-api/internal/service"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

// DashboardHandler handles dashboard-related API endpoints
type DashboardHandler struct {
	db             *gorm.DB
	logDB          *gorm.DB
	statsService   *service.StatsService
	logPartitioner *service.LogPartitioner
}

// NewDashboardHandler creates a new DashboardHandler
func NewDashboardHandler(db *gorm.DB, logDB *gorm.DB, statsService *service.StatsService, logPartitioner *service.LogPartitioner) *DashboardHandler {
	if logDB == nil {
		logDB = db
	}
	return &DashboardHandler{
		db:             db,
		logDB:          logDB,
		statsService:   statsService,
		logPartitioner: logPartitioner,
	}
}

func (h *DashboardHandler) logDBConn() *gorm.DB {
	if h == nil || h.logDB == nil {
		return h.db
	}
	return h.logDB
}

func (h *DashboardHandler) logBaseQuery() *gorm.DB {
	return logBaseQuery(h.logDBConn(), h.logPartitioner)
}

// RequestStats contains request-related statistics
type RequestStats struct {
	Total     int64   `json:"total"`
	Success   int64   `json:"success"`
	Failed    int64   `json:"failed"`
	ErrorRate float64 `json:"error_rate"`
}

// TokenStats contains token usage statistics
type TokenStats struct {
	Total  int64 `json:"total"`
	Input  int64 `json:"input"`
	Output int64 `json:"output"`
}

// LatencyStats contains latency statistics
type LatencyStats struct {
	AvgMs float64 `json:"avg_ms"`
}

// CountStats contains simple count statistics
type CountStats struct {
	Total  int64 `json:"total"`
	Active int64 `json:"active"`
}

// ProviderKeyStats contains provider key statistics
type ProviderKeyStats struct {
	Total        int64 `json:"total"`
	Active       int64 `json:"active"`
	Suspended    int64 `json:"suspended"`
	AutoDisabled int64 `json:"auto_disabled"`
}

// TopModelStat contains model usage statistics
type TopModelStat struct {
	Model    string `json:"model"`
	Requests int64  `json:"requests"`
	Tokens   int64  `json:"tokens"`
}

// DashboardSummaryResponse is the response for dashboard summary endpoint
type DashboardSummaryResponse struct {
	Period       string           `json:"period,omitempty"`
	Requests     RequestStats     `json:"requests"`
	Tokens       TokenStats       `json:"tokens"`
	Latency      LatencyStats     `json:"latency"`
	Masters      CountStats       `json:"masters"`
	Keys         CountStats       `json:"keys"`
	ProviderKeys ProviderKeyStats `json:"provider_keys"`
	TopModels    []TopModelStat   `json:"top_models"`
	UpdatedAt    int64            `json:"updated_at"`
}

// GetSummary godoc
// @Summary      Dashboard summary
// @Description  Returns aggregated metrics for dashboard display including requests, tokens, latency, masters, keys, and provider keys statistics
// @Tags         admin
// @Produce      json
// @Security     AdminAuth
// @Param        period  query     string  false  "time period: today, week, month, all"
// @Param        since   query     int     false  "unix seconds"
// @Param        until   query     int     false  "unix seconds"
// @Success      200  {object}  DashboardSummaryResponse
// @Failure      400  {object}  gin.H
// @Failure      500  {object}  gin.H
// @Router       /admin/dashboard/summary [get]
func (h *DashboardHandler) GetSummary(c *gin.Context) {
	rng, err := parseStatsRange(c)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Build log query with time range
	logQuery := h.logBaseQuery()
	logQuery = applyStatsRange(logQuery, rng)

	// 1. Request statistics
	var totalRequests int64
	if err := logQuery.Session(&gorm.Session{}).Count(&totalRequests).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count requests", "details": err.Error()})
		return
	}

	type statusCount struct {
		StatusCode int
		Cnt        int64
	}
	var statusCounts []statusCount
	if err := logQuery.Session(&gorm.Session{}).
		Select("status_code, COUNT(*) as cnt").
		Group("status_code").
		Scan(&statusCounts).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count by status", "details": err.Error()})
		return
	}

	var successCount, failedCount int64
	for _, sc := range statusCounts {
		if sc.StatusCode >= 200 && sc.StatusCode < 400 {
			successCount += sc.Cnt
		} else {
			failedCount += sc.Cnt
		}
	}

	errorRate := 0.0
	if totalRequests > 0 {
		errorRate = float64(failedCount) / float64(totalRequests)
	}

	// 2. Token statistics
	type tokenSums struct {
		TokensIn   int64
		TokensOut  int64
		AvgLatency float64
	}
	var ts tokenSums
	if err := logQuery.Session(&gorm.Session{}).
		Select("COALESCE(SUM(tokens_in),0) as tokens_in, COALESCE(SUM(tokens_out),0) as tokens_out, COALESCE(AVG(latency_ms),0) as avg_latency").
		Scan(&ts).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to aggregate tokens", "details": err.Error()})
		return
	}

	// 3. Master statistics
	var totalMasters, activeMasters int64
	if err := h.db.Model(&model.Master{}).Count(&totalMasters).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count masters", "details": err.Error()})
		return
	}
	if err := h.db.Model(&model.Master{}).Where("status = ?", "active").Count(&activeMasters).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count active masters", "details": err.Error()})
		return
	}

	// 4. Key (child token) statistics
	var totalKeys, activeKeys int64
	if err := h.db.Model(&model.Key{}).Count(&totalKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count keys", "details": err.Error()})
		return
	}
	if err := h.db.Model(&model.Key{}).Where("status = ?", "active").Count(&activeKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count active keys", "details": err.Error()})
		return
	}

	// 5. Provider key statistics
	var totalProviderKeys, activeProviderKeys, suspendedProviderKeys, autoDisabledProviderKeys int64
	if err := h.db.Model(&model.APIKey{}).Count(&totalProviderKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count provider keys", "details": err.Error()})
		return
	}
	if err := h.db.Model(&model.APIKey{}).Where("status = ?", "active").Count(&activeProviderKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count active provider keys", "details": err.Error()})
		return
	}
	if err := h.db.Model(&model.APIKey{}).Where("status = ?", "suspended").Count(&suspendedProviderKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count suspended provider keys", "details": err.Error()})
		return
	}
	if err := h.db.Model(&model.APIKey{}).Where("status = ?", "auto_disabled").Count(&autoDisabledProviderKeys).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count auto_disabled provider keys", "details": err.Error()})
		return
	}

	// 6. Top models (limit to 10)
	type modelStat struct {
		ModelName string
		Cnt       int64
		Tokens    int64
	}
	var topModels []modelStat
	if err := logQuery.Session(&gorm.Session{}).
		Select("model_name, COUNT(*) as cnt, COALESCE(SUM(tokens_in + tokens_out),0) as tokens").
		Group("model_name").
		Order("cnt DESC").
		Limit(10).
		Scan(&topModels).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to get top models", "details": err.Error()})
		return
	}

	topModelStats := make([]TopModelStat, 0, len(topModels))
	for _, m := range topModels {
		topModelStats = append(topModelStats, TopModelStat{
			Model:    m.ModelName,
			Requests: m.Cnt,
			Tokens:   m.Tokens,
		})
	}

	c.JSON(http.StatusOK, DashboardSummaryResponse{
		Period: rng.Period,
		Requests: RequestStats{
			Total:     totalRequests,
			Success:   successCount,
			Failed:    failedCount,
			ErrorRate: errorRate,
		},
		Tokens: TokenStats{
			Total:  ts.TokensIn + ts.TokensOut,
			Input:  ts.TokensIn,
			Output: ts.TokensOut,
		},
		Latency: LatencyStats{
			AvgMs: ts.AvgLatency,
		},
		Masters: CountStats{
			Total:  totalMasters,
			Active: activeMasters,
		},
		Keys: CountStats{
			Total:  totalKeys,
			Active: activeKeys,
		},
		ProviderKeys: ProviderKeyStats{
			Total:        totalProviderKeys,
			Active:       activeProviderKeys,
			Suspended:    suspendedProviderKeys,
			AutoDisabled: autoDisabledProviderKeys,
		},
		TopModels: topModelStats,
		UpdatedAt: time.Now().UTC().Unix(),
	})
}