// Package handlers provides HTTP request handlers.
package handlers

import (
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"time"

	"go.uber.org/fx"
	"sneak.berlin/go/pixa/internal/config"
	"sneak.berlin/go/pixa/internal/database"
	"sneak.berlin/go/pixa/internal/encurl"
	"sneak.berlin/go/pixa/internal/healthcheck"
	"sneak.berlin/go/pixa/internal/imgcache"
	"sneak.berlin/go/pixa/internal/logger"
	"sneak.berlin/go/pixa/internal/session"
)

// Params defines dependencies for Handlers.
type Params struct {
	fx.In
	Logger      *logger.Logger
	Healthcheck *healthcheck.Healthcheck
	Database    *database.Database
	Config      *config.Config
}

// Handlers provides HTTP request handlers.
type Handlers struct {
	log      *slog.Logger
	hc       *healthcheck.Healthcheck
	db       *database.Database
	config   *config.Config
	imgSvc   *imgcache.Service
	imgCache *imgcache.Cache
	sessMgr  *session.Manager
	encGen   *encurl.Generator
}

// New creates a new Handlers instance.
func New(lc fx.Lifecycle, params Params) (*Handlers, error) {
	s := &Handlers{
		log:    params.Logger.Get(),
		hc:     params.Healthcheck,
		db:     params.Database,
		config: params.Config,
	}

	lc.Append(fx.Hook{
		OnStart: func(_ context.Context) error {
			return s.initImageService()
		},
	})

	return s, nil
}

// initImageService initializes the image cache and service.
func (s *Handlers) initImageService() error {
	// Create the cache
	cache, err := imgcache.NewCache(s.db.DB(), imgcache.CacheConfig{
		StateDir:        s.config.StateDir,
		CacheTTL:        imgcache.DefaultCacheTTL,
		NegativeTTL:     imgcache.DefaultNegativeTTL,
		HotCacheSize:    imgcache.DefaultHotCacheSize,
		HotCacheEnabled: true,
	})
	if err != nil {
		return err
	}

	s.imgCache = cache

	// Create the fetcher config
	fetcherCfg := imgcache.DefaultFetcherConfig()
	fetcherCfg.AllowHTTP = s.config.AllowHTTP
	if s.config.UpstreamConnectionsPerHost > 0 {
		fetcherCfg.MaxConnectionsPerHost = s.config.UpstreamConnectionsPerHost
	}

	// Create the service
	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
		Cache:         cache,
		FetcherConfig: fetcherCfg,
		SigningKey:    s.config.SigningKey,
		Whitelist:     s.config.WhitelistHosts,
		Logger:        s.log,
	})
	if err != nil {
		return err
	}

	s.imgSvc = svc
	s.log.Info("image service initialized")

	// Initialize session manager and URL generator if signing key is configured
	if s.config.SigningKey != "" {
		sessMgr, err := session.NewManager(s.config.SigningKey, !s.config.Debug)
		if err != nil {
			return err
		}
		s.sessMgr = sessMgr

		encGen, err := encurl.NewGenerator(s.config.SigningKey)
		if err != nil {
			return err
		}
		s.encGen = encGen

		s.log.Info("session manager and URL generator initialized")
	}

	return nil
}

func (s *Handlers) respondJSON(w http.ResponseWriter, data interface{}, status int) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if data != nil {
		err := json.NewEncoder(w).Encode(data)
		if err != nil {
			s.log.Error("json encode error", "error", err)
		}
	}
}

func (s *Handlers) respondError(w http.ResponseWriter, message string, status int) {
	s.respondJSON(w, map[string]interface{}{
		"error":     message,
		"status":    status,
		"timestamp": time.Now().UTC().Format(time.RFC3339),
	}, status)
}