package router

import (
	"context"
	"log"
	"net/http"
	"net/url"
	"os"
	"sync"
	"time"

	"bookhoard/internal/database"
	"bookhoard/internal/handlers"
	"bookhoard/internal/services"
	"bookhoard/internal/utils"
	"bookhoard/templates"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/labstack/echo/v5"
)

func getTemplateUserWithTheme(c *echo.Context, cfg *Config) (templates.User, error) {
	userID := c.Get("user_id").(string)
	userEmail := c.Get("user_email").(string)
	userUsername := c.Get("user_username").(string)
	userRole := c.Get("user_role").(string)

	userUUID, err := uuid.Parse(userID)
	if err != nil {
		log.Printf("getTemplateUserWithTheme failed: invalid UUID '%s': %v", userID, err)
		return templates.User{}, err
	}

	userDB, err := cfg.Queries.GetUser(c.Request().Context(), uuidToPGType(userUUID))
	if err != nil {
		log.Printf("getTemplateUserWithTheme failed: database query error for user ID %s: %v", userID, err)
		return templates.User{}, err
	}

	userTheme := "tokyo-night"
	if userDB.Theme.Valid {
		userTheme = userDB.Theme.String
	}

	userTimezone := "UTC"
	if userDB.Timezone.Valid {
		userTimezone = userDB.Timezone.String
	}

	// Extract JWT token for WebSocket authentication
	token := ""
	if cookie, err := c.Cookie("token"); err == nil {
		token = cookie.Value
	}

	return templates.User{
		ID:        userID,
		Email:     userEmail,
		Username:  userUsername,
		Role:      userRole,
		Theme:     userTheme,
		Token:     token,
		Timezone:  userTimezone,
		FirstName: utils.PgTextString(userDB.FirstName),
		LastName:  utils.PgTextString(userDB.LastName),
		CreatedAt: userDB.CreatedAt.Time,
	}, nil
}

func convertPending(pending []map[string]interface{}) []templates.PendingRegistrationData {
	result := make([]templates.PendingRegistrationData, len(pending))
	for i, p := range pending {
		result[i] = templates.PendingRegistrationData{
			RegistrationID: p["registration_id"].(string),
			DeviceName:     p["device_name"].(string),
			DeviceType:     p["device_type"].(string),
			ExpiresAt:      p["expires_at"].(time.Time).Format(time.RFC3339),
		}
	}
	return result
}

func pingDB(cfg *Config, ctx context.Context) error {
	if cfg.DBPool != nil {
		if pool, ok := cfg.DBPool.(*pgxpool.Pool); ok {
			return pool.Ping(ctx)
		}
	}
	return nil
}

func parseUUID(s string) (uuid.UUID, error) {
	return uuid.Parse(s)
}

func uuidToPGType(u uuid.UUID) pgtype.UUID {
	return pgtype.UUID{Bytes: u, Valid: true}
}

const selectedLibraryCookie = "selectedLibrary"
const allLibrariesSentinel = "__all__"

type LibraryResolution struct {
	LibraryID string
	IsAll     bool
	LibUUID   pgtype.UUID
	Libraries []templates.LibraryData
	FirstID   string
}

// folderStatEntry caches one folder-reachability result.
type folderStatEntry struct {
	exists bool
	at     time.Time
}

const folderStatTTL = 30 * time.Second

var folderStatCache sync.Map

// folderReachableCached stats a library folder with a short TTL cache:
// resolveLibrary runs on every SSR render, and a stat per library folder
// over a network mount adds real latency to each page. The cache trades
// ~30s of stale online/offline state for snappy renders.
func folderReachableCached(path string) bool {
	if v, ok := folderStatCache.Load(path); ok {
		if e, ok := v.(folderStatEntry); ok && time.Since(e.at) < folderStatTTL {
			return e.exists
		}
	}
	exists := false
	if _, err := os.Stat(path); err == nil {
		exists = true
	}
	folderStatCache.Store(path, folderStatEntry{exists: exists, at: time.Now()})
	return exists
}

func resolveLibrary(c *echo.Context, cfg *Config, userUUID string) LibraryResolution {
	res := LibraryResolution{}

	userU, _ := uuid.Parse(userUUID)
	libraries, err := cfg.Queries.GetUserVisibleLibraries(c.Request().Context(), uuidToPGType(userU))
	if err != nil {
		log.Printf("GetUserVisibleLibraries failed: %v", err)
		libraries = []database.GetUserVisibleLibrariesRow{}
	}
	visibleSet := make(map[string]bool, len(libraries))
	for _, lib := range libraries {
		if !lib.ID.Valid {
			continue
		}
		if id, err := uuid.FromBytes(lib.ID.Bytes[0:16]); err == nil {
			visibleSet[id.String()] = true
		}
	}

	counts, countErr := cfg.Queries.GetVisibleLibraryMediaCounts(c.Request().Context(), uuidToPGType(userU))
	if countErr != nil {
		log.Printf("GetVisibleLibraryMediaCounts failed: %v", countErr)
		counts = []database.GetVisibleLibraryMediaCountsRow{}
	}
	countMap := make(map[string]int64, len(counts))
	for _, mc := range counts {
		mcUUID, _ := uuid.FromBytes(mc.ID.Bytes[0:16])
		countMap[mcUUID.String()] = mc.MediaCount
	}

	res.Libraries = make([]templates.LibraryData, len(libraries))
	for i, lib := range libraries {
		libUUID, _ := uuid.FromBytes(lib.ID.Bytes[0:16])
		// Steam Deck SD-card behavior: a library whose folders are all
		// missing (unmounted drive) renders offline - hidden contents, no
		// marking, no purging - and returns when the storage does.
		offline := false
		folders, folderErr := cfg.Queries.GetLibraryFolders(c.Request().Context(), lib.ID)
		if folderErr != nil || len(folders) == 0 {
			offline = true
		} else {
			anyFolderExists := false
			for _, folder := range folders {
				if folderReachableCached(folder.FolderPath) {
					anyFolderExists = true
					break
				}
			}
			offline = !anyFolderExists
		}
		res.Libraries[i] = templates.LibraryData{
			ID:          libUUID.String(),
			Name:        lib.Name,
			Description: utils.PgTextString(lib.Description),
			TypeName:    lib.TypeName,
			TypeValue:   lib.TypeName,
			MediaCount:  countMap[libUUID.String()],
			Offline:     offline,
		}
	}

	if len(libraries) > 0 {
		libUUID, _ := uuid.FromBytes(libraries[0].ID.Bytes[0:16])
		res.FirstID = libUUID.String()
	}

	libraryID := c.QueryParam("library_id")
	if libraryID == "" {
		if cookie, err := c.Cookie(selectedLibraryCookie); err == nil {
			val, _ := url.QueryUnescape(cookie.Value)
			if val == allLibrariesSentinel {
				res.IsAll = true
				res.LibraryID = ""
				return res
			}
			if _, parseErr := uuid.Parse(val); parseErr == nil {
				libraryID = val
			}
		}
	}

	if libraryID == "" {
		res.LibraryID = res.FirstID
		if res.LibraryID != "" {
			parsed, _ := uuid.Parse(res.LibraryID)
			res.LibUUID = pgtype.UUID{Bytes: parsed, Valid: true}
		}
		return res
	}

	// A requested library outside the requester's visible set is not
	// honored — fall back to the first visible library instead of leaking
	// hidden-library contents through a hand-typed query param or cookie.
	if !visibleSet[libraryID] {
		res.LibraryID = res.FirstID
		if res.LibraryID != "" {
			parsed, _ := uuid.Parse(res.LibraryID)
			res.LibUUID = pgtype.UUID{Bytes: parsed, Valid: true}
		}
		return res
	}

	res.LibraryID = libraryID
	parsed, _ := uuid.Parse(libraryID)
	res.LibUUID = pgtype.UUID{Bytes: parsed, Valid: true}
	return res
}

// visibleLibraryIDsFor returns the requester's visible-library id set (for
// membership checks) plus the ids themselves (for SQL ANY() filters).
func visibleLibraryIDsFor(c *echo.Context, cfg *Config) (map[string]bool, []pgtype.UUID, error) {
	userUUIDStr, ok := c.Get("user_id").(string)
	if !ok {
		return nil, nil, echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	userU, err := uuid.Parse(userUUIDStr)
	if err != nil {
		return nil, nil, echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	return cfg.LibraryService.VisibleLibrarySet(c.Request().Context(), uuidToPGType(userU))
}

// collectionDataFromRow builds the template collection payload shared by
// the collection detail page and its books-grid partial.
func collectionDataFromRow(collection database.Collections, collectionID string, isSmart bool, bookCount int) templates.CollectionData {
	return templates.CollectionData{
		ID:          collectionID,
		Name:        collection.Name,
		Description: collection.Description.String,
		Color:       collection.Color.String,
		Icon:        collection.Icon.String,
		IsSystem:    collection.IsSystemCollection.Bool,
		IsSmart:     isSmart,
		BookCount:   bookCount,
	}
}

// collectionBooksForScope runs the per-scope book loading shared by the
// detail page and the books-grid partial: smart evaluation, a dashboard
// query section, or manual membership. Callers resolve the scope:
// libUUID/libScope/isAll/scoped per their own resolution rules.
func (cfg *Config) collectionBooksForScope(c *echo.Context, userUUID uuid.UUID, collUUID pgtype.UUID, collection database.Collections, collectionID string, libUUID pgtype.UUID, libScope pgtype.UUID, scoped bool, visibleIDs []pgtype.UUID) (books []handlers.BookInfo, isSmart bool, errCode string) {
	colService := cfg.CollectionHandler.CollectionService()
	isSmart = colService.IsSmartCollection(collection.AutoAssignRules)
	libTypes := handlers.LibraryTypeMap(c.Request().Context(), cfg.Queries)

	if isSmart {
		// Smart (dynamic) collection: membership is evaluated live —
		// visible libraries, live items only, any enabled rule matches.
		matches, evalErr := colService.EvaluateSmartCollection(c.Request().Context(),
			colService.ParseRules(collection.AutoAssignRules), services.SmartEvalOptions{
				LibraryID:  libScope,
				VisibleIDs: visibleIDs,
			})
		if evalErr != nil {
			return nil, isSmart, "books_load_error"
		}
		books = handlers.BookCardsFromMediaItems(matches, libTypes)
	} else if collection.IsSystemCollection.Bool && collection.QueryType.Valid && collection.QueryType.String != "" && collection.QueryType.String != "filter" {
		dashboardSvc := services.NewDashboardService(cfg.Queries)
		sections, secErr := dashboardSvc.GetDashboardSections(c.Request().Context(), userUUID, libUUID, 1000, []string{}, []string{})
		if secErr != nil {
			return nil, isSmart, "books_load_error"
		}

		for _, section := range sections {
			if section.CollectionID.String() == collectionID {
				books = handlers.BookCardsFromMediaItems(section.Items, libTypes)
				break
			}
		}
	} else {
		if scoped && libUUID.Valid {
			collItems, collErr := cfg.Queries.GetCollectionItemsForDashboard(c.Request().Context(),
				database.GetCollectionItemsForDashboardParams{
					CollectionID: collUUID,
					LibraryID:    libUUID,
					Limit:        pgtype.Int4{Int32: 1000, Valid: true},
				})
			if collErr != nil {
				books = handlers.BookCardsFromCollectionDashRows(nil, libTypes)
			} else {
				// The query filters excluded rows in SQL.
				books = handlers.BookCardsFromCollectionDashRows(collItems, libTypes)
			}
		} else {
			collItems, collErr := cfg.Queries.GetCollectionItems(c.Request().Context(), collUUID)
			if collErr != nil {
				collItems = nil
			}
			books = handlers.BookCardsFromCollectionItemRows(collItems, libTypes)
		}
	}
	return books, isSmart, ""
}

// loadCollectionBooks resolves the books shown for a collection detail
// page: full library resolution (visible-library payload, folder
// reachability, counts) because the page render needs it. The books-grid
// partial uses the lighter loadCollectionBooksLite instead.
// errCode is "" on success, otherwise a renderErrorPage code.
func (cfg *Config) loadCollectionBooks(c *echo.Context, user templates.User, collection database.Collections, collectionID string) (books []handlers.BookInfo, libRes LibraryResolution, isSmart bool, errCode string) {
	collUUID, parseErr := uuid.Parse(collectionID)
	if parseErr != nil {
		return nil, libRes, isSmart, "invalid_id"
	}
	userUUID, _ := uuid.Parse(user.ID)

	libRes = resolveLibrary(c, cfg, user.ID)
	libraryID := libRes.LibraryID

	var libScope pgtype.UUID
	if !libRes.IsAll {
		if parsed, parseErr := uuid.Parse(libraryID); parseErr == nil {
			libScope = pgtype.UUID{Bytes: parsed, Valid: true}
		}
	}

	visibleIDs, visErr := cfg.CollectionHandler.UserVisibleLibraryIDs(c)
	if visErr != nil {
		log.Printf("UserVisibleLibraryIDs failed: %v", visErr)
		visibleIDs = nil
	}

	scoped := libraryID != "" && !libRes.IsAll
	books, isSmart, errCode = cfg.collectionBooksForScope(c, userUUID, pgtype.UUID{Bytes: collUUID, Valid: true}, collection, collectionID, libRes.LibUUID, libScope, scoped, visibleIDs)
	return books, libRes, isSmart, errCode
}

// loadCollectionBooksLite is the books-grid partial's loader. The switcher
// refresh only needs "is the requested library visible, and its books" —
// so it validates the requested library against the caller's visible set
// directly (family-lens: out-of-set is rejected) and skips the page-only
// library resolution (folder reachability, counts, dropdown payload).
func (cfg *Config) loadCollectionBooksLite(c *echo.Context, userUUID uuid.UUID, collection database.Collections, collectionID string) (books []handlers.BookInfo, isSmart bool, errCode string) {
	collUUID, parseErr := uuid.Parse(collectionID)
	if parseErr != nil {
		return nil, isSmart, "invalid_id"
	}
	libraryID := c.QueryParam("library_id")

	var libUUID pgtype.UUID
	if libraryID != "" {
		parsed, parseErr := uuid.Parse(libraryID)
		if parseErr != nil {
			return nil, isSmart, "invalid_library_id"
		}
		set, _, setErr := cfg.LibraryService.VisibleLibrarySet(
			c.Request().Context(), pgtype.UUID{Bytes: userUUID, Valid: true})
		if setErr != nil {
			return nil, isSmart, "books_load_error"
		}
		if !set[libraryID] {
			return nil, isSmart, "library_forbidden"
		}
		libUUID = pgtype.UUID{Bytes: parsed, Valid: true}
	}

	visibleIDs, visErr := cfg.CollectionHandler.UserVisibleLibraryIDs(c)
	if visErr != nil {
		log.Printf("UserVisibleLibraryIDs failed: %v", visErr)
		visibleIDs = nil
	}

	return cfg.collectionBooksForScope(c, userUUID, pgtype.UUID{Bytes: collUUID, Valid: true}, collection, collectionID,
		libUUID, libUUID, libraryID != "", visibleIDs)
}

// libraryTypeOptionsFor loads the library_types rows for the create-library
// dropdowns (admin page + setup wizard), ordered for display. On DB failure
// it falls back to the built-in type names so the form stays usable —
// CreateLibrary resolves the name against the DB, so this is never
// authoritative.
func libraryTypeOptionsFor(ctx context.Context, cfg *Config) []database.LibraryTypes {
	types, err := cfg.LibraryService.GetLibraryTypes(ctx)
	if err != nil {
		log.Printf("libraryTypeOptionsFor: GetLibraryTypes failed, using built-in type names: %v", err)
		for _, name := range []string{
			services.LibraryTypeEbooks,
			services.LibraryTypeComics,
			services.LibraryTypeManga,
			services.LibraryTypeAudiobooks,
		} {
			types = append(types, database.LibraryTypes{Name: name})
		}
	}
	return templates.OrderedLibraryTypes(types)
}