package handler

import (
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/mattnite/cairn/internal/models"
	"gorm.io/gorm"
)

type DashboardHandler struct {
	DB *gorm.DB
}

type DashboardStats struct {
	TotalArtifacts   int64 `json:"total_artifacts"`
	TotalRepos       int64 `json:"total_repos"`
	TotalCrashGroups int64 `json:"total_crash_groups"`
	OpenCrashGroups  int64 `json:"open_crash_groups"`
	TotalTargets     int64 `json:"total_targets"`
}

type TrendPoint struct {
	Date  string `json:"date"`
	Count int64  `json:"count"`
}

type TopCrasher struct {
	Title           string `json:"title"`
	OccurrenceCount uint   `json:"occurrence_count"`
	RepoName        string `json:"repo_name"`
	CrashGroupID    uint   `json:"crash_group_id"`
}

type DashboardResponse struct {
	Stats       DashboardStats `json:"stats"`
	Trend       []TrendPoint   `json:"trend"`
	TopCrashers []TopCrasher   `json:"top_crashers"`
}

func (h *DashboardHandler) Stats(c *gin.Context) {
	ctx := c.Request.Context()
	var stats DashboardStats

	_ = h.DB.WithContext(ctx).Model(&models.Artifact{}).Count(&stats.TotalArtifacts).Error
	_ = h.DB.WithContext(ctx).Model(&models.Repository{}).Count(&stats.TotalRepos).Error
	_ = h.DB.WithContext(ctx).Model(&models.CrashGroup{}).Count(&stats.TotalCrashGroups).Error
	_ = h.DB.WithContext(ctx).Model(&models.CrashGroup{}).Where("status = ?", "open").Count(&stats.OpenCrashGroups).Error
	_ = h.DB.WithContext(ctx).Model(&models.Target{}).Count(&stats.TotalTargets).Error

	// Artifact trend for the last 30 days.
	var trend []TrendPoint
	type trendRow struct {
		Day   time.Time
		Count int64
	}
	var rows []trendRow
	err := h.DB.WithContext(ctx).
		Table("artifacts").
		Select("DATE(created_at) as day, COUNT(*) as count").
		Where("created_at >= ?", time.Now().AddDate(0, 0, -30)).
		Group("day").
		Order("day").
		Scan(&rows).Error
	if err == nil {
		for _, row := range rows {
			trend = append(trend, TrendPoint{Date: row.Day.Format("2006-01-02"), Count: row.Count})
		}
	}

	// Top crashers (most frequent open crash groups).
	var groups []models.CrashGroup
	err = h.DB.WithContext(ctx).Where("status = ?", "open").Order("last_seen_at DESC").Limit(50).Find(&groups).Error
	topCrashers := make([]TopCrasher, 0, 10)
	if err == nil {
		for _, group := range groups {
			fullGroup, fullErr := models.GetCrashGroup(ctx, h.DB, group.ID)
			if fullErr != nil {
				continue
			}
			topCrashers = append(topCrashers, TopCrasher{
				CrashGroupID:    fullGroup.ID,
				Title:           fullGroup.Title,
				OccurrenceCount: fullGroup.OccurrenceCount,
				RepoName:        fullGroup.RepoName,
			})
			if len(topCrashers) == 10 {
				break
			}
		}
	}

	c.JSON(http.StatusOK, DashboardResponse{
		Stats:       stats,
		Trend:       trend,
		TopCrashers: topCrashers,
	})
}