package handlers

import (
	"bytes"
	"fmt"
	"image"
	"image/jpeg"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

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

	xdraw "golang.org/x/image/draw"
	_ "golang.org/x/image/webp"

	"go_blog/models"
)

// ProfilePage renders the profile edit page.
func ProfilePage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		session := sessions.Default(c)
		userID := session.Get("user_id")

		var user models.User
		if err := db.First(&user, userID).Error; err != nil {
			c.String(http.StatusInternalServerError, "User not found")
			return
		}

		data := DefaultData(c)
		data["Title"] = tr["profile_title"]
		data["Profile"] = user

		// Flash messages (success / error).
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["profile_saved"]
		}
		if msg := c.Query("error"); msg == "pw" {
			data["Error"] = tr["profile_wrong_password"]
		}
		switch c.Query("error") {
		case "upload":
			data["Error"] = tr["profile_upload_invalid"]
		case "upload_disabled":
			data["Error"] = tr["profile_upload_disabled"]
		case "size":
			data["Error"] = fmt.Sprintf(tr["profile_upload_too_large"], c.Query("max"))
		}

		c.HTML(http.StatusOK, "profile", data)
	}
}

// UpdateProfile processes the profile edit form (multipart).
func UpdateProfile(db *gorm.DB, storagePath string) gin.HandlerFunc {
	return func(c *gin.Context) {
		session := sessions.Default(c)
		userID := session.Get("user_id")

		var user models.User
		if err := db.First(&user, userID).Error; err != nil {
			c.Redirect(http.StatusFound, "/profile")
			return
		}

		// --- Text fields ---
		if v := c.PostForm("display_name"); v != "" {
			user.DisplayName = v
		}
		if v := c.PostForm("gender"); v != "" {
			user.Gender = v
		}
		if v := c.PostForm("email"); v != "" {
			user.Email = v
		}
		if v := c.PostForm("birthday"); v != "" {
			if t, err := time.Parse("2006-01-02", v); err == nil {
				user.Birthday = &t
			}
		}

		// --- Avatar upload ---
		file, header, err := c.Request.FormFile("avatar")
		if err == nil {
			defer file.Close()

			// Validate against the platform upload policy (switch + type + size).
			check := ValidateUpload(header)
			if !check.OK {
				session.Save()
				reason := "?error=upload"
				if !models.GetUploadConfig().Enabled {
					reason = "?error=upload_disabled"
				} else if check.Type != nil {
					reason = fmt.Sprintf("?error=size&max=%s", formatSize(check.MaxSize))
				}
				c.Redirect(http.StatusFound, "/profile"+reason)
				return
			}

			// Determine file extension (validated to be in the whitelist).
			ext := strings.ToLower(filepath.Ext(header.Filename))

			// Save under storagePath/avatars/.
			avatarDir := filepath.Join(storagePath, "avatars")
			if err := os.MkdirAll(avatarDir, 0755); err != nil {
				c.Redirect(http.StatusFound, "/profile")
				return
			}

			// Remove old avatar file if it exists (different extension or same).
			if user.Avatar != "" {
				oldPath := filepath.Join(avatarDir, user.Avatar)
				os.Remove(oldPath) // ignore error — file may not exist
			}

			// Use user ID as filename base.
			savedName := fmt.Sprintf("%d%s", user.ID, ext)
			savedPath := filepath.Join(avatarDir, savedName)

			dst, err := os.Create(savedPath)
			if err != nil {
				c.Redirect(http.StatusFound, "/profile")
				return
			}
			defer dst.Close()

			if _, err := io.Copy(dst, file); err != nil {
				c.Redirect(http.StatusFound, "/profile")
				return
			}

			user.Avatar = savedName
			session.Set("avatar", savedName)
		}

		// --- Password change ---
		currentPass := c.PostForm("current_password")
		newPass := c.PostForm("new_password")
		if currentPass != "" && newPass != "" {
			if !user.CheckPassword(currentPass) {
				session.Save()
				c.Redirect(http.StatusFound, "/profile?error=pw")
				return
			}
			if err := user.SetPassword(newPass); err != nil {
				session.Save()
				c.Redirect(http.StatusFound, "/profile")
				return
			}
		}

		// Save user record.
		if err := db.Save(&user).Error; err != nil {
			session.Save()
			c.Redirect(http.StatusFound, "/profile")
			return
		}

		// Update display name in session.
		session.Set("display_name", user.DisplayName)
		session.Save()

		c.Redirect(http.StatusFound, "/profile?saved=1")
	}
}

// UploadAvatar handles AJAX avatar upload with cropping.
func UploadAvatar(db *gorm.DB, storagePath string) gin.HandlerFunc {
	return func(c *gin.Context) {
		session := sessions.Default(c)
		userID := session.Get("user_id")

		var user models.User
		if err := db.First(&user, userID).Error; err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "User not found"})
			return
		}

		file, header, err := c.Request.FormFile("avatar")
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "No file provided"})
			return
		}
		defer file.Close()

		// Validate against the platform upload policy (switch + type + size).
		check := ValidateUpload(header)
		if !check.OK {
			if !models.GetUploadConfig().Enabled {
				c.JSON(http.StatusBadRequest, gin.H{"error": "uploads are disabled"})
				return
			}
			if check.Type != nil {
				c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("file too large; limit is %s", formatSize(check.MaxSize))})
				return
			}
			c.JSON(http.StatusBadRequest, gin.H{"error": "file type not allowed"})
			return
		}

		// Determine file extension (validated to be in the whitelist).
		ext := strings.ToLower(filepath.Ext(header.Filename))

		// Read file bytes for image processing.
		imgBytes, err := io.ReadAll(file)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to read file"})
			return
		}

		// Decode, resize, and re-encode the image.
		processedBytes, finalExt, err := processAvatar(imgBytes, ext)
		if err != nil {
			// Fall back to saving raw bytes if processing fails.
			processedBytes = imgBytes
			finalExt = ext
		}

		// Ensure avatar directory exists.
		avatarDir := filepath.Join(storagePath, "avatars")
		os.MkdirAll(avatarDir, 0755)

		// Remove old avatar file.
		if user.Avatar != "" {
			oldPath := filepath.Join(avatarDir, user.Avatar)
			os.Remove(oldPath)
		}

		// Save processed avatar.
		savedName := fmt.Sprintf("%d%s", user.ID, finalExt)
		savedPath := filepath.Join(avatarDir, savedName)
		if err := os.WriteFile(savedPath, processedBytes, 0644); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to save avatar"})
			return
		}

		// Update user record.
		user.Avatar = savedName
		db.Save(&user)

		// Update session.
		session.Set("avatar", savedName)
		session.Save()

		c.JSON(http.StatusOK, gin.H{"avatar": savedName})
	}
}

// processAvatar decodes, resizes to 256x256, and re-encodes an avatar image as JPEG.
func processAvatar(imgBytes []byte, ext string) ([]byte, string, error) {
	src, _, err := image.Decode(bytes.NewReader(imgBytes))
	if err != nil {
		return nil, "", err
	}

	const targetSize = 256
	dst := image.NewRGBA(image.Rect(0, 0, targetSize, targetSize))
	xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, src.Bounds(), xdraw.Src, nil)

	var buf bytes.Buffer
	if err := jpeg.Encode(&buf, dst, &jpeg.Options{Quality: 85}); err != nil {
		return nil, "", err
	}

	return buf.Bytes(), ".jpg", nil
}