package handlers

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

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

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

type DevicesHandler struct {
	db *gorm.DB
}

func NewDevicesHandler(db *gorm.DB) *DevicesHandler { return &DevicesHandler{db: db} }

func (h *DevicesHandler) 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
	}

	// Get user context
	userContext, exists := c.Get("user")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
		return
	}

	user, ok := userContext.(UserContext)
	if !ok {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid user data"})
		return
	}

	var total int64
	var devs []models.Device
	var err error

	if user.Role == models.RoleAdmin {
		// Admin user - show all devices
		err = h.db.Model(&models.Device{}).Count(&total).Error
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "count query failed: " + err.Error()})
			return
		}

		err = h.db.Preload("Users").Offset(offset).Limit(limit).Find(&devs).Error
	} else {
		err = h.db.Model(&models.Device{}).
			Joins("INNER JOIN user_devices ON user_devices.id = devices.guid").
			Where("user_devices.guid = ?", user.ID).
			Count(&total).Error

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

		err = h.db.Preload("Users").
			Joins("INNER JOIN user_devices ON user_devices.id = devices.guid").
			Where("user_devices.guid = ?", user.ID).
			Offset(offset).Limit(limit).
			Find(&devs).Error
	}

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

	out := make([]dto.DeviceDto, 0, len(devs))
	for _, d := range devs {
		out = append(out, dto.MapDevice(d))
	}

	c.JSON(http.StatusOK, dto.DeviceListDto{Devices: out, Offset: offset, Limit: limit, Total: total})
}

func (h *DevicesHandler) Create(c *gin.Context) {
	var req dto.CreateDeviceDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	d := models.Device{GUID: req.GUID, Name: req.Name}
	if err := h.db.Create(&d).Error; err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "device exists?"})
		return
	}
	// Optional initial user assignments
	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(&d).Association("Users").Append(&users); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "link failed"})
			return
		}
	}
	// Return with users
	var withUsers models.Device
	if err := h.db.Preload("Users").Where("guid = ?", d.GUID).First(&withUsers).Error; err != nil {
		c.JSON(http.StatusCreated, dto.DeviceDto{GUID: d.GUID, Name: d.Name})
		return
	}
	c.JSON(http.StatusCreated, dto.MapDevice(withUsers))
}

func (h *DevicesHandler) Rename(c *gin.Context) {
	guid := c.Param("guid")
	var d models.Device
	if err := h.db.Where("guid = ?", guid).First(&d).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "device not found"})
		return
	}
	var req dto.RenameDeviceDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	d.Name = req.Name
	if err := h.db.Save(&d).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "save failed"})
		return
	}
	c.JSON(http.StatusCreated, dto.DeviceDto{GUID: d.GUID, Name: d.Name})
}

func (h *DevicesHandler) AddToUser(c *gin.Context) {
	guid := c.Param("guid")
	var d models.Device
	if err := h.db.Where("guid = ?", guid).First(&d).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "device not found"})
		return
	}
	var req dto.EditDeviceToUserRelationDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	ids := req.UserIDs
	if req.UserID != 0 {
		ids = append(ids, req.UserID)
	}
	if len(ids) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "userIds or userId required"})
		return
	}

	users, err := h.fetchUsers(ids)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if err := h.db.Model(&d).Association("Users").Append(&users); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "link failed"})
		return
	}
	var withUsers models.Device
	_ = h.db.Preload("Users").Where("guid = ?", d.GUID).First(&withUsers).Error
	c.JSON(http.StatusCreated, dto.MapDevice(withUsers))
}

// SetUsers replaces the users of a device with the provided list.
// Passing an empty list clears all assignments (covers the "no user assigned" case).
func (h *DevicesHandler) SetUsers(c *gin.Context) {
	guid := c.Param("guid")
	var d models.Device
	if err := h.db.Where("guid = ?", guid).First(&d).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "device not found"})
		return
	}
	var req dto.SetDeviceUsersDto
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	// Load users (if any)
	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
	}
	// Replace association: Clear() then Append(new)
	if err := h.db.Model(&d).Association("Users").Clear(); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "clear failed"})
		return
	}
	if len(users) > 0 {
		if err := h.db.Model(&d).Association("Users").Append(&users); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "link failed"})
			return
		}
	}
	var withUsers models.Device
	_ = h.db.Preload("Users").Where("guid = ?", d.GUID).First(&withUsers).Error
	c.JSON(http.StatusCreated, dto.MapDevice(withUsers))
}

func (h *DevicesHandler) RemoveFromUser(c *gin.Context) {
	guid := c.Param("guid")
	var d models.Device
	if err := h.db.Where("guid = ?", guid).First(&d).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "device not found"})
		return
	}
	var req dto.RemoveDeviceUsersDto
	_ = c.ShouldBindJSON(&req) // ignore error; we support query fallback

	ids := make([]uint, 0, len(req.UserIDs)+1)
	if req.UserID != 0 {
		ids = append(ids, req.UserID)
	}
	if len(req.UserIDs) > 0 {
		ids = append(ids, req.UserIDs...)
	}
	// query fallback
	if len(ids) == 0 {
		if q := strings.TrimSpace(c.Query("userId")); q != "" {
			if n, err := strconv.Atoi(q); err == nil && n > 0 {
				ids = append(ids, uint(n))
			}
		}
		if q := strings.TrimSpace(c.Query("userIds")); q != "" {
			for _, p := range strings.Split(q, ",") {
				p = strings.TrimSpace(p)
				if n, err := strconv.Atoi(p); err == nil && n > 0 {
					ids = append(ids, uint(n))
				}
			}
		}
	}
	if len(ids) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "userIds or userId required"})
		return
	}

	users, err := h.fetchUsers(ids)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}
	if len(users) == 0 {
		c.JSON(http.StatusOK, dto.DeviceDto{GUID: d.GUID, Name: d.Name})
		return
	}
	if err := h.db.Model(&d).Association("Users").Delete(&users); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "unlink failed"})
		return
	}
	var withUsers models.Device
	_ = h.db.Preload("Users").Where("guid = ?", d.GUID).First(&withUsers).Error
	c.JSON(http.StatusOK, dto.MapDevice(withUsers))
}

func (h *DevicesHandler) 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
}

func (h *DevicesHandler) ListCertsByDevice(c *gin.Context) {
	guid := c.Param("guid")
	var d models.Device
	if err := h.db.Where("guid = ?", guid).First(&d).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "device not found"})
		return
	}
	var list []models.DeviceCertificate
	if err := h.db.Where("device_guid = ?", guid).Order("id desc").Find(&list).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "query failed"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"certs": list})
}