package handlers

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

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

	"go_blog/models"
)

// mbToBytes converts a megabyte count (string) to bytes. Returns 0 on parse
// failure. Values <= 0 are treated as 0 (meaning "use default" for per-type
// limits).
func mbToBytes(s string) int64 {
	s = strings.TrimSpace(s)
	if s == "" {
		return 0
	}
	n, err := strconv.ParseFloat(s, 64)
	if err != nil {
		return 0
	}
	return int64(n * 1024 * 1024)
}

// bytesToMB renders a byte count as megabytes (one decimal) for form display.
func bytesToMB(b int64) string {
	return fmt.Sprintf("%.1f", float64(b)/float64(1024*1024))
}

// userIDFromSession extracts the logged-in user's ID, or 0 if absent. It
// defends against int/uint/int64/float64 storage in the session.
func userIDFromSession(c *gin.Context) uint {
	session := sessions.Default(c)
	userID := session.Get("user_id")
	if userID == nil {
		return 0
	}
	switch v := userID.(type) {
	case uint:
		return v
	case int:
		return uint(v)
	case int64:
		return uint(v)
	case float64:
		return uint(v)
	}
	return 0
}

// ---------------- Site settings ----------------

// SiteSettingsPage renders the site display settings form.
func SiteSettingsPage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		var s models.SiteSetting
		if err := db.First(&s, 1).Error; err != nil {
			s = models.SiteSetting{ID: 1}
		}

		data := DefaultData(c)
		data["Title"] = tr["settings_site_title"]
		data["Site"] = s
		// Pre-compute derived values so the template never invokes methods on
		// an interface{}-wrapped struct (which Go templates cannot resolve).
		data["SiteLogoIsURL"] = s.LogoIsURL()
		data["SiteFaviconIsURL"] = s.FaviconIsURL()
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["settings_saved"]
		}
		c.HTML(http.StatusOK, "settings_site", data)
	}
}

// SiteSettingsSave handles logo upload and text fields for site settings.
func SiteSettingsSave(db *gorm.DB, storagePath string) gin.HandlerFunc {
	return func(c *gin.Context) {
		var s models.SiteSetting
		if err := db.First(&s, 1).Error; err != nil {
			s = models.SiteSetting{ID: 1}
		}

		s.LogoTextZh = strings.TrimSpace(c.PostForm("logo_text_zh"))
		s.LogoTextEn = strings.TrimSpace(c.PostForm("logo_text_en"))
		s.HeaderTextZh = strings.TrimSpace(c.PostForm("header_text_zh"))
		s.HeaderTextEn = strings.TrimSpace(c.PostForm("header_text_en"))
		s.HomeWelcomeZh = strings.TrimSpace(c.PostForm("home_welcome_zh"))
		s.HomeWelcomeEn = strings.TrimSpace(c.PostForm("home_welcome_en"))
		s.HomeSubtitleZh = strings.TrimSpace(c.PostForm("home_subtitle_zh"))
		s.HomeSubtitleEn = strings.TrimSpace(c.PostForm("home_subtitle_en"))
		s.FooterTextZh = strings.TrimSpace(c.PostForm("footer_text_zh"))
		s.FooterTextEn = strings.TrimSpace(c.PostForm("footer_text_en"))
		s.AllowRegistration = c.PostForm("allow_registration") == "1"
		s.UpdatedBy = userIDFromSession(c)

		// Favicon upload (optional). A favicon_url form field takes precedence over an
		// uploaded file, so admins can set either a local file or an external link.
		if faviconURL := strings.TrimSpace(c.PostForm("favicon_url")); faviconURL != "" {
			s.Favicon = faviconURL
		} else if file, header, err := c.Request.FormFile("favicon"); err == nil {
			defer file.Close()
			check := ValidateUpload(header)
			if !check.OK || check.Type.Category != models.CategoryImage {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			logoDir := filepath.Join(storagePath, "logos")
			os.MkdirAll(logoDir, 0755)
			// Remove the previous local favicon (skip external URLs).
			if s.Favicon != "" && !s.FaviconIsURL() {
				os.Remove(filepath.Join(logoDir, s.Favicon))
			}
			ext := strings.ToLower(filepath.Ext(header.Filename))
			savedName := fmt.Sprintf("favicon%s", ext)
			dst, err := os.Create(filepath.Join(logoDir, savedName))
			if err != nil {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			defer dst.Close()
			if _, err := io.Copy(dst, file); err != nil {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			s.Favicon = savedName
		}

		// Remove favicon entirely if requested.
		if c.PostForm("favicon_clear") == "1" {
			if s.Favicon != "" && !s.FaviconIsURL() {
				os.Remove(filepath.Join(storagePath, "logos", s.Favicon))
			}
			s.Favicon = ""
		}

		// Logo upload (optional). A logo_url form field takes precedence over an
		// uploaded file, so admins can set either a local file or an external link.
		if logoURL := strings.TrimSpace(c.PostForm("logo_url")); logoURL != "" {
			s.Logo = logoURL
		} else if file, header, err := c.Request.FormFile("logo"); err == nil {
			defer file.Close()
			check := ValidateUpload(header)
			if !check.OK || check.Type.Category != models.CategoryImage {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			logoDir := filepath.Join(storagePath, "logos")
			os.MkdirAll(logoDir, 0755)
			// Remove the previous local logo (skip external URLs).
			if s.Logo != "" && !s.LogoIsURL() {
				os.Remove(filepath.Join(logoDir, s.Logo))
			}
			ext := strings.ToLower(filepath.Ext(header.Filename))
			savedName := fmt.Sprintf("logo%s", ext)
			dst, err := os.Create(filepath.Join(logoDir, savedName))
			if err != nil {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			defer dst.Close()
			if _, err := io.Copy(dst, file); err != nil {
				c.Redirect(http.StatusFound, "/admin/settings/site")
				return
			}
			s.Logo = savedName
		}

		// Remove logo entirely if requested.
		if c.PostForm("logo_clear") == "1" {
			if s.Logo != "" && !s.LogoIsURL() {
				os.Remove(filepath.Join(storagePath, "logos", s.Logo))
			}
			s.Logo = ""
		}

		if err := db.Save(&s).Error; err != nil {
			c.Redirect(http.StatusFound, "/admin/settings/site")
			return
		}
		models.RefreshConfigCache(db)
		c.Redirect(http.StatusFound, "/admin/settings/site?saved=1")
	}
}

// ---------------- Upload settings ----------------

// fileTypeView augments an UploadFileType with a pre-rendered max-size MB
// string for the template (avoids needing a template FuncMap for division).
type fileTypeView struct {
	models.UploadFileType
	MaxSizeMB string
}

// UploadSettingsPage renders the upload policy + file-type management page.
func UploadSettingsPage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		var u models.UploadConfig
		if err := db.First(&u, 1).Error; err != nil {
			u = models.UploadConfig{ID: 1, Enabled: true, DefaultMaxSize: models.DefaultUploadMaxSize, StorageDir: "attachments"}
		}
		var types []models.UploadFileType
		db.Order("category asc, sort asc, id asc").Find(&types)

		views := make([]fileTypeView, 0, len(types))
		for _, t := range types {
			views = append(views, fileTypeView{UploadFileType: t, MaxSizeMB: bytesToMB(t.MaxSize)})
		}

		data := DefaultData(c)
		data["Title"] = tr["settings_upload_title"]
		data["Upload"] = u
		data["FileTypes"] = views
		data["DefaultMaxSizeMB"] = bytesToMB(u.DefaultMaxSize)
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["settings_saved"]
		}
		c.HTML(http.StatusOK, "settings_upload", data)
	}
}

// UploadSettingsSave dispatches upload-config and file-type actions.
func UploadSettingsSave(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		switch c.PostForm("action") {
		case "save_config":
			saveUploadConfig(db, c)
		case "add_type":
			addUploadFileType(db, c)
		case "toggle_type":
			toggleUploadFileType(db, c)
		case "size_type":
			sizeUploadFileType(db, c)
		case "delete_type":
			deleteUploadFileType(db, c)
		}
		models.RefreshConfigCache(db)
		c.Redirect(http.StatusFound, "/admin/settings/upload?saved=1")
	}
}

func saveUploadConfig(db *gorm.DB, c *gin.Context) {
	var u models.UploadConfig
	if err := db.First(&u, 1).Error; err != nil {
		u = models.UploadConfig{ID: 1}
	}
	u.Enabled = c.PostForm("enabled") == "1"
	u.DefaultMaxSize = mbToBytes(c.PostForm("default_max_size"))
	if u.DefaultMaxSize <= 0 {
		u.DefaultMaxSize = models.DefaultUploadMaxSize
	}
	if dir := strings.TrimSpace(c.PostForm("storage_dir")); dir != "" {
		u.StorageDir = dir
	}
	u.UpdatedBy = userIDFromSession(c)
	db.Save(&u)
}

func addUploadFileType(db *gorm.DB, c *gin.Context) {
	ext := strings.ToLower(strings.TrimSpace(c.PostForm("extension")))
	if ext == "" {
		return
	}
	if !strings.HasPrefix(ext, ".") {
		ext = "." + ext
	}
	t := models.UploadFileType{
		Extension: ext,
		MimeType:  strings.TrimSpace(c.PostForm("mime_type")),
		Category:  strings.TrimSpace(c.PostForm("category")),
		MaxSize:   mbToBytes(c.PostForm("max_size")),
		Enabled:   c.PostForm("enabled") != "0",
		Sort:      50,
	}
	if t.Category == "" {
		t.Category = models.CategoryOther
	}
	// Ignore duplicate-extension errors silently.
	db.Where("extension = ?", t.Extension).FirstOrCreate(&t)
}

func toggleUploadFileType(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	var t models.UploadFileType
	if db.First(&t, id).Error != nil {
		return
	}
	t.Enabled = !t.Enabled
	db.Save(&t)
}

func sizeUploadFileType(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	var t models.UploadFileType
	if db.First(&t, id).Error != nil {
		return
	}
	t.MaxSize = mbToBytes(c.PostForm("max_size"))
	db.Save(&t)
}

func deleteUploadFileType(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	db.Delete(&models.UploadFileType{}, id)
}

// ---------------- Download settings ----------------

// DownloadSettingsPage renders the download base-URL management page.
func DownloadSettingsPage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		var urls []models.DownloadBaseURL
		db.Order("is_default desc, priority asc, id asc").Find(&urls)

		data := DefaultData(c)
		data["Title"] = tr["settings_download_title"]
		data["BaseURLs"] = urls
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["settings_saved"]
		}
		c.HTML(http.StatusOK, "settings_download", data)
	}
}

// DownloadSettingsSave dispatches download base-URL actions.
func DownloadSettingsSave(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		switch c.PostForm("action") {
		case "add":
			addDownloadBaseURL(db, c)
		case "toggle":
			toggleDownloadBaseURL(db, c)
		case "default":
			defaultDownloadBaseURL(db, c)
		case "delete":
			deleteDownloadBaseURL(db, c)
		}
		models.RefreshConfigCache(db)
		c.Redirect(http.StatusFound, "/admin/settings/download?saved=1")
	}
}

func addDownloadBaseURL(db *gorm.DB, c *gin.Context) {
	name := strings.TrimSpace(c.PostForm("name"))
	base := strings.TrimSpace(c.PostForm("base_url"))
	if base == "" {
		return
	}
	prio, _ := strconv.Atoi(c.PostForm("priority"))
	b := models.DownloadBaseURL{
		Name:     name,
		BaseURL:  base,
		Priority: prio,
		Enabled:  c.PostForm("enabled") != "0",
	}
	db.Create(&b)
}

func toggleDownloadBaseURL(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	var b models.DownloadBaseURL
	if db.First(&b, id).Error != nil {
		return
	}
	b.Enabled = !b.Enabled
	db.Save(&b)
}

func defaultDownloadBaseURL(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	// Only one default at a time.
	db.Model(&models.DownloadBaseURL{}).Where("1=1").Update("is_default", false)
	db.Model(&models.DownloadBaseURL{}).Where("id = ?", id).Update("is_default", true)
}

func deleteDownloadBaseURL(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	db.Delete(&models.DownloadBaseURL{}, id)
}

// ---------------- Comment settings ----------------

// CommentSettingsPage renders the comment policy form.
func CommentSettingsPage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		var cc models.CommentConfig
		if err := db.First(&cc, 1).Error; err != nil {
			cc = *models.GetCommentConfig()
		}

		data := DefaultData(c)
		data["Title"] = tr["comment_settings_title"]
		data["CommentConfig"] = cc
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["settings_saved"]
		}
		c.HTML(http.StatusOK, "settings_comment", data)
	}
}

// CommentSettingsSave persists the comment policy toggles and refreshes the
// in-memory cache so subsequent requests see the change.
func CommentSettingsSave(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		var cc models.CommentConfig
		if err := db.First(&cc, 1).Error; err != nil {
			cc = models.CommentConfig{ID: 1}
		}
		cc.Enabled = c.PostForm("enabled") == "1"
		cc.AllowGuest = c.PostForm("allow_guest") == "1"
		cc.GuestRequireApproval = c.PostForm("guest_require_approval") == "1"
		cc.UseGravatar = c.PostForm("use_gravatar") == "1"
		cc.UpdatedBy = userIDFromSession(c)
		db.Save(&cc)
		models.RefreshConfigCache(db)
		c.Redirect(http.StatusFound, "/admin/settings/comments?saved=1")
	}
}

// ---------------- Navigation Links settings ----------------

// NavLinksSettingsPage renders the navigation links management page.
func NavLinksSettingsPage(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		tr := getTr(c)
		var links []models.NavLink
		db.Order("sort asc, id asc").Find(&links)

		data := DefaultData(c)
		data["Title"] = tr["settings_navlinks_title"]
		data["NavLinks"] = links
		if msg := c.Query("saved"); msg == "1" {
			data["Success"] = tr["settings_saved"]
		}
		c.HTML(http.StatusOK, "settings_navlinks", data)
	}
}

// NavLinksSettingsSave dispatches navigation link actions.
func NavLinksSettingsSave(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		switch c.PostForm("action") {
		case "add":
			addNavLink(db, c)
		case "toggle":
			toggleNavLink(db, c)
		case "edit":
			editNavLink(db, c)
		case "delete":
			deleteNavLink(db, c)
		}
		models.RefreshConfigCache(db)
		c.Redirect(http.StatusFound, "/admin/settings/navlinks?saved=1")
	}
}

func addNavLink(db *gorm.DB, c *gin.Context) {
	titleZh := strings.TrimSpace(c.PostForm("title_zh"))
	titleEn := strings.TrimSpace(c.PostForm("title_en"))
	url := strings.TrimSpace(c.PostForm("url"))

	if url == "" || (titleZh == "" && titleEn == "") {
		return
	}

	sort, _ := strconv.Atoi(c.PostForm("sort"))

	link := models.NavLink{
		TitleZh:  titleZh,
		TitleEn:  titleEn,
		URL:      url,
		OpenNew:  c.PostForm("open_new") == "1",
		Enabled:  c.PostForm("enabled") != "0",
		Sort:     sort,
		UpdatedBy: userIDFromSession(c),
	}
	db.Create(&link)
}

func toggleNavLink(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	var link models.NavLink
	if db.First(&link, id).Error != nil {
		return
	}
	link.Enabled = !link.Enabled
	link.UpdatedBy = userIDFromSession(c)
	db.Save(&link)
}

func editNavLink(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	var link models.NavLink
	if db.First(&link, id).Error != nil {
		return
	}

	titleZh := strings.TrimSpace(c.PostForm("title_zh"))
	titleEn := strings.TrimSpace(c.PostForm("title_en"))
	url := strings.TrimSpace(c.PostForm("url"))

	if url == "" || (titleZh == "" && titleEn == "") {
		return
	}

	link.TitleZh = titleZh
	link.TitleEn = titleEn
	link.URL = url
	link.OpenNew = c.PostForm("open_new") == "1"
	link.Sort, _ = strconv.Atoi(c.PostForm("sort"))
	link.UpdatedBy = userIDFromSession(c)
	db.Save(&link)
}

func deleteNavLink(db *gorm.DB, c *gin.Context) {
	id, _ := strconv.Atoi(c.PostForm("id"))
	db.Delete(&models.NavLink{}, id)
}