package handlers

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"smoop-api/internal/dto"
	"smoop-api/internal/models"
)

type TrackersHandler struct {
	db *gorm.DB
}

func NewTrackersHandler(db *gorm.DB) *TrackersHandler { return &TrackersHandler{db: db} }

// GET /trackers — list trackers available for user (admin: all)
func (h *TrackersHandler) List(c *gin.Context) {
	offset, _ := strconv.Atoi(c.DefaultQuery("offset", "0"))
	limit, _ := strconv.Atoi(c.DefaultQuery("limit", "50"))
	if limit <= 0 || limit > 200 {
		limit = 50
	}

	// Default behavior (fallback if middleware not present): use user context
	isFilter := true
	var userID uint

	if v, ok := c.Get("filterTrackers"); ok {
		if b, ok2 := v.(bool); ok2 {
			isFilter = b
		}
	}
	if v, ok := c.Get("userID"); ok {
		if id, ok2 := v.(uint); ok2 {
			userID = id
		}
	}

	// Fallback to claims if middleware wasn’t applied
	if _, exists := c.Get("filterTrackers"); !exists {
		if uc, ok := GetUserContext(c); ok {
			if uc.Role == models.RoleAdmin {
				isFilter = false
			} else {
				isFilter = true
				userID = uc.ID
			}
		} else {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
			return
		}
	}

	var (
		total int64
		list  []models.Tracker
		err   error
	)

	if !isFilter {
		// Admin: all trackers
		err = h.db.Model(&models.Tracker{}).Count(&total).Error
		if err == nil {
			err = h.db.Preload("Users").Offset(offset).Limit(limit).Find(&list).Error
		}
	} else {
		// Filtered by userID
		q := h.db.Model(&models.Tracker{}).
			Joins("JOIN user_trackers ut ON ut.tracker_guid = trackers.guid").
			Where("ut.user_id = ?", userID)
		if err = q.Count(&total).Error; err == nil {
			err = h.db.Preload("Users").
				Joins("JOIN user_trackers ut ON ut.tracker_guid = trackers.guid").
				Where("ut.user_id = ?", userID).
				Offset(offset).Limit(limit).
				Find(&list).Error
		}
	}

	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "query failed: " + err.Error()})
		return
	}

	out := make([]dto.TrackerDto, 0, len(list))
	for _, t := range list {
		out = append(out, dto.MapTracker(t))
	}
	c.JSON(http.StatusOK, dto.TrackerListDto{
		Trackers: out, Offset: offset, Limit: limit, Total: total,
	})
}

// POST /trackers/create — create tracker; optional initial user assignments
func (h *TrackersHandler) Create(c *gin.Context) {
	var req dto.CreateTrackerDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	t := models.Tracker{GUID: req.GUID, Name: req.Name}
	if err := h.db.Create(&t).Error; err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "tracker exists?"})
		return
	}
	// optional users
	if len(req.UserIDs) > 0 {
		users, err := h.fetchUsers(req.UserIDs)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}
		if err := h.db.Model(&t).Association("Users").Append(&users); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "link failed"})
			return
		}
	}
	var withUsers models.Tracker
	if err := h.db.Preload("Users").Where("guid = ?", t.GUID).First(&withUsers).Error; err != nil {
		c.JSON(http.StatusCreated, dto.TrackerDto{GUID: t.GUID, Name: t.Name})
		return
	}
	c.JSON(http.StatusCreated, dto.MapTracker(withUsers))
}

// POST /trackers/:guid/rename — rename tracker
func (h *TrackersHandler) Rename(c *gin.Context) {
	guid := c.Param("guid")
	var t models.Tracker
	if err := h.db.Where("guid = ?", guid).First(&t).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "tracker not found"})
		return
	}
	var req dto.RenameTrackerDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	t.Name = req.Name
	if err := h.db.Save(&t).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "save failed"})
		return
	}
	c.JSON(http.StatusCreated, dto.TrackerDto{GUID: t.GUID, Name: t.Name})
}

// POST /trackers/:guid/set_users — replace full user list (admin)
func (h *TrackersHandler) SetUsers(c *gin.Context) {
	guid := c.Param("guid")
	var t models.Tracker
	if err := h.db.Where("guid = ?", guid).First(&t).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "tracker not found"})
		return
	}
	var req dto.SetTrackerUsersDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	users := []models.User{}
	if len(req.UserIDs) > 0 {
		found, err := h.fetchUsers(req.UserIDs)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}
		users = found
	}
	if err := h.db.Model(&t).Association("Users").Clear(); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "clear failed"})
		return
	}
	if len(users) > 0 {
		if err := h.db.Model(&t).Association("Users").Append(&users); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "link failed"})
			return
		}
	}
	var withUsers models.Tracker
	_ = h.db.Preload("Users").Where("guid = ?", t.GUID).First(&withUsers).Error
	c.JSON(http.StatusCreated, dto.MapTracker(withUsers))
}

// local helper (same as devices.go)
func (h *TrackersHandler) fetchUsers(ids []uint) ([]models.User, error) {
	unique := make(map[uint]struct{}, len(ids))
	clean := make([]uint, 0, len(ids))
	for _, id := range ids {
		if id != 0 {
			if _, ok := unique[id]; !ok {
				unique[id] = struct{}{}
				clean = append(clean, id)
			}
		}
	}
	if len(clean) == 0 {
		return nil, nil
	}
	var users []models.User
	if err := h.db.Find(&users, clean).Error; err != nil {
		return nil, err
	}
	if len(users) != len(clean) {
		return nil, fmt.Errorf("some users not found")
	}
	return users, nil
}