package handlers

import (
	"errors"
	"net/http"
	"time"

	"github.com/celestia-trace/backend/models"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type SyncHandler struct {
	DB *gorm.DB
}

func defaultSyncSetting(userID string) models.SyncSetting {
	return models.SyncSetting{
		UserID:             userID,
		AutoSyncWiFi:       true,
		SyncPhotos:         true,
		SyncAudio:          true,
		AudioQuality:       "HD",
		CloudStorageMaxMB:  5120,
		CloudStorageUsedMB: 0,
	}
}

// GetSyncSettings returns the user sync settings and storage status
func (h *SyncHandler) GetSyncSettings(c *gin.Context) {
	userID := c.GetString("userID")

	var setting models.SyncSetting
	err := h.DB.First(&setting, "user_id = ?", userID).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		setting = defaultSyncSetting(userID)
		h.DB.Create(&setting)
	}
	var totalBytes int64
	h.DB.Model(&models.MediaAsset{}).Where("user_id = ?", userID).Select("COALESCE(SUM(size_bytes), 0)").Scan(&totalBytes)
	setting.CloudStorageUsedMB = (totalBytes + 1024*1024 - 1) / (1024 * 1024)

	respondSuccess(c, setting)
}

// UpdateSyncSettings updates sync settings
func (h *SyncHandler) UpdateSyncSettings(c *gin.Context) {
	userID := c.GetString("userID")
	var req models.UpdateSyncSettingRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		respondError(c, http.StatusBadRequest, 400, "invalid parameters")
		return
	}

	var setting models.SyncSetting
	if err := h.DB.First(&setting, "user_id = ?", userID).Error; err != nil {
		setting = defaultSyncSetting(userID)
	}

	if req.AutoSyncWiFi != nil {
		setting.AutoSyncWiFi = *req.AutoSyncWiFi
	}
	if req.SyncPhotos != nil {
		setting.SyncPhotos = *req.SyncPhotos
	}
	if req.SyncAudio != nil {
		setting.SyncAudio = *req.SyncAudio
	}
	if req.AudioQuality != nil {
		setting.AudioQuality = *req.AudioQuality
	}

	now := time.Now()
	setting.LastSyncedAt = &now

	if err := h.DB.Save(&setting).Error; err != nil {
		respondError(c, http.StatusInternalServerError, 500, "failed to update sync settings")
		return
	}

	respondSuccess(c, setting)
}

// GetSyncSummary returns aggregated stats (devices, sessions, total duration, storage)
func (h *SyncHandler) GetSyncSummary(c *gin.Context) {
	userID := c.GetString("userID")

	var deviceCount int64
	h.DB.Model(&models.BoundDevice{}).Where("user_id = ?", userID).Count(&deviceCount)

	var sessionCount int64
	h.DB.Model(&models.CelestiaSession{}).Where("user_id = ? AND deleted_at IS NULL", userID).Count(&sessionCount)

	var totalDurationMs int64
	h.DB.Model(&models.CelestiaSession{}).Where("user_id = ? AND deleted_at IS NULL", userID).Select("COALESCE(SUM(duration_ms), 0)").Scan(&totalDurationMs)

	var setting models.SyncSetting
	if err := h.DB.First(&setting, "user_id = ?", userID).Error; err != nil {
		setting = defaultSyncSetting(userID)
		h.DB.Create(&setting)
	}
	var totalBytes int64
	h.DB.Model(&models.MediaAsset{}).Where("user_id = ?", userID).Select("COALESCE(SUM(size_bytes), 0)").Scan(&totalBytes)
	setting.CloudStorageUsedMB = (totalBytes + 1024*1024 - 1) / (1024 * 1024)

	summary := models.SyncSummary{
		DeviceCount:     deviceCount,
		SessionCount:    sessionCount,
		TotalDurationMs: totalDurationMs,
		Storage:         setting,
	}

	respondSuccess(c, summary)
}

// TriggerManualSync records a completed client checkpoint. It does not claim
// that local files were uploaded; the client only calls this after all uploads.
func (h *SyncHandler) TriggerManualSync(c *gin.Context) {
	userID := c.GetString("userID")
	now := time.Now()

	var setting models.SyncSetting
	if err := h.DB.First(&setting, "user_id = ?", userID).Error; err == nil {
		setting.LastSyncedAt = &now
		h.DB.Save(&setting)
	}

	respondSuccess(c, gin.H{
		"syncedAt": now,
		"message":  "Client sync checkpoint recorded",
	})
}

// GetStorageQuota returns the user's storage quota and current usage in bytes.
// The iOS client calls GET /storage/quota before uploading large files.
func (h *SyncHandler) GetStorageQuota(c *gin.Context) {
	userID := c.GetString("userID")

	var setting models.SyncSetting
	if err := h.DB.First(&setting, "user_id = ?", userID).Error; err != nil {
		setting = defaultSyncSetting(userID)
		h.DB.Create(&setting)
	}

	var usedBytes int64
	h.DB.Model(&models.MediaAsset{}).Where("user_id = ?", userID).
		Select("COALESCE(SUM(size_bytes), 0)").Scan(&usedBytes)

	totalBytes := setting.CloudStorageMaxMB * 1024 * 1024
	remainingBytes := totalBytes - usedBytes
	if remainingBytes < 0 {
		remainingBytes = 0
	}

	respondSuccess(c, gin.H{
		"totalBytes":     totalBytes,
		"usedBytes":      usedBytes,
		"remainingBytes": remainingBytes,
	})
}