package api

import (
	"crypto/rand"
	"embed"
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	"github.com/gin-contrib/multitemplate"
	"github.com/gin-contrib/sessions"
	"github.com/gin-contrib/sessions/cookie"
	"github.com/gin-gonic/gin"
	"github.com/microcosm-cc/bluemonday"
	log "github.com/sirupsen/logrus"
	"reichard.io/bbank/config"
	"reichard.io/bbank/database"
)

type API struct {
	Router     *gin.Engine
	Config     *config.Config
	DB         *database.DBManager
	HTMLPolicy *bluemonday.Policy
	Assets     *embed.FS
	Templates  map[string]*template.Template
}

func NewApi(db *database.DBManager, c *config.Config, assets *embed.FS) *API {
	api := &API{
		HTMLPolicy: bluemonday.StrictPolicy(),
		Router:     gin.Default(),
		Config:     c,
		DB:         db,
		Assets:     assets,
	}

	// Assets & Web App Templates
	assetsDir, _ := fs.Sub(assets, "assets")
	api.Router.StaticFS("/assets", http.FS(assetsDir))

	// Generate Secure Token
	var newToken []byte
	var err error

	if c.CookieSessionKey != "" {
		log.Info("[NewApi] Utilizing Environment Cookie Session Key")
		newToken = []byte(c.CookieSessionKey)
	} else {
		log.Info("[NewApi] Generating Cookie Session Key")
		newToken, err = generateToken(64)
		if err != nil {
			panic("Unable to generate secure token")
		}
	}

	// Configure Cookie Session Store
	store := cookie.NewStore(newToken)
	store.Options(sessions.Options{
		MaxAge:   60 * 60 * 24 * 7,
		Secure:   c.CookieSecure,
		HttpOnly: c.CookieHTTPOnly,
		SameSite: http.SameSiteStrictMode,
	})
	api.Router.Use(sessions.Sessions("token", store))

	// Register Web App Route
	api.registerWebAppRoutes()

	// Register API Routes
	apiGroup := api.Router.Group("/api")
	api.registerKOAPIRoutes(apiGroup)
	api.registerOPDSRoutes(apiGroup)

	return api
}

func (api *API) registerWebAppRoutes() {
	// Generate Templates
	api.Router.HTMLRender = *api.generateTemplates()

	// Static Assets (Required @ Root)
	api.Router.GET("/manifest.json", api.webManifest)
	api.Router.GET("/favicon.ico", api.faviconIcon)
	api.Router.GET("/sw.js", api.serviceWorker)

	// Local / Offline Static Pages (No Template, No Auth)
	api.Router.GET("/local", api.localDocuments)

	// Reader (Reader Page, Document Progress, Devices)
	api.Router.GET("/reader", api.documentReader)
	api.Router.GET("/reader/devices", api.authWebAppMiddleware, api.getDevices)
	api.Router.GET("/reader/progress/:document", api.authWebAppMiddleware, api.getDocumentProgress)

	// Web App
	api.Router.GET("/", api.authWebAppMiddleware, api.createAppResourcesRoute("home"))
	api.Router.GET("/activity", api.authWebAppMiddleware, api.createAppResourcesRoute("activity"))
	api.Router.GET("/documents", api.authWebAppMiddleware, api.createAppResourcesRoute("documents"))
	api.Router.GET("/documents/:document", api.authWebAppMiddleware, api.createAppResourcesRoute("document"))
	api.Router.GET("/documents/:document/cover", api.authWebAppMiddleware, api.getDocumentCover)
	api.Router.GET("/documents/:document/file", api.authWebAppMiddleware, api.downloadDocument)
	api.Router.GET("/login", api.createAppResourcesRoute("login"))
	api.Router.GET("/logout", api.authWebAppMiddleware, api.authLogout)
	api.Router.GET("/register", api.createAppResourcesRoute("login", gin.H{"Register": true}))
	api.Router.GET("/settings", api.authWebAppMiddleware, api.createAppResourcesRoute("settings"))
	api.Router.POST("/login", api.authFormLogin)
	api.Router.POST("/register", api.authFormRegister)

	// Demo Mode Enabled Configuration
	if api.Config.DemoMode {
		api.Router.POST("/documents", api.authWebAppMiddleware, api.demoModeAppError)
		api.Router.POST("/documents/:document/delete", api.authWebAppMiddleware, api.demoModeAppError)
		api.Router.POST("/documents/:document/edit", api.authWebAppMiddleware, api.demoModeAppError)
		api.Router.POST("/documents/:document/identify", api.authWebAppMiddleware, api.demoModeAppError)
		api.Router.POST("/settings", api.authWebAppMiddleware, api.demoModeAppError)
	} else {
		api.Router.POST("/documents", api.authWebAppMiddleware, api.uploadNewDocument)
		api.Router.POST("/documents/:document/delete", api.authWebAppMiddleware, api.deleteDocument)
		api.Router.POST("/documents/:document/edit", api.authWebAppMiddleware, api.editDocument)
		api.Router.POST("/documents/:document/identify", api.authWebAppMiddleware, api.identifyDocument)
		api.Router.POST("/settings", api.authWebAppMiddleware, api.editSettings)
	}

	// Search Enabled Configuration
	if api.Config.SearchEnabled {
		api.Router.GET("/search", api.authWebAppMiddleware, api.createAppResourcesRoute("search"))
		api.Router.POST("/search", api.authWebAppMiddleware, api.saveNewDocument)
	}
}

func (api *API) registerKOAPIRoutes(apiGroup *gin.RouterGroup) {
	koGroup := apiGroup.Group("/ko")

	// KO Sync Routes (WebApp Uses - Progress & Activity)
	koGroup.GET("/documents/:document/file", api.authKOMiddleware, api.downloadDocument)
	koGroup.GET("/syncs/progress/:document", api.authKOMiddleware, api.getProgress)
	koGroup.GET("/users/auth", api.authKOMiddleware, api.authorizeUser)
	koGroup.POST("/activity", api.authKOMiddleware, api.addActivities)
	koGroup.POST("/syncs/activity", api.authKOMiddleware, api.checkActivitySync)
	koGroup.POST("/users/create", api.createUser)
	koGroup.PUT("/syncs/progress", api.authKOMiddleware, api.setProgress)

	// Demo Mode Enabled Configuration
	if api.Config.DemoMode {
		koGroup.POST("/documents", api.authKOMiddleware, api.demoModeJSONError)
		koGroup.POST("/syncs/documents", api.authKOMiddleware, api.demoModeJSONError)
		koGroup.PUT("/documents/:document/file", api.authKOMiddleware, api.demoModeJSONError)
	} else {
		koGroup.POST("/documents", api.authKOMiddleware, api.addDocuments)
		koGroup.POST("/syncs/documents", api.authKOMiddleware, api.checkDocumentsSync)
		koGroup.PUT("/documents/:document/file", api.authKOMiddleware, api.uploadExistingDocument)
	}
}

func (api *API) registerOPDSRoutes(apiGroup *gin.RouterGroup) {
	opdsGroup := apiGroup.Group("/opds")

	// OPDS Routes
	opdsGroup.GET("", api.authOPDSMiddleware, api.opdsEntry)
	opdsGroup.GET("/", api.authOPDSMiddleware, api.opdsEntry)
	opdsGroup.GET("/search.xml", api.authOPDSMiddleware, api.opdsSearchDescription)
	opdsGroup.GET("/documents", api.authOPDSMiddleware, api.opdsDocuments)
	opdsGroup.GET("/documents/:document/cover", api.authOPDSMiddleware, api.getDocumentCover)
	opdsGroup.GET("/documents/:document/file", api.authOPDSMiddleware, api.downloadDocument)
}

func (api *API) generateTemplates() *multitemplate.Renderer {
	// Define Templates & Helper Functions
	templates := make(map[string]*template.Template)
	render := multitemplate.NewRenderer()
	helperFuncs := template.FuncMap{
		"GetSVGGraphData": getSVGGraphData,
		"GetUTCOffsets":   getUTCOffsets,
		"NiceSeconds":     niceSeconds,
		"dict":            dict,
	}

	// Load Base
	b, _ := api.Assets.ReadFile("templates/base.html")
	baseTemplate := template.Must(template.New("base").Funcs(helperFuncs).Parse(string(b)))

	// Load SVGs
	svgs, _ := api.Assets.ReadDir("templates/svgs")
	for _, item := range svgs {
		basename := item.Name()
		path := fmt.Sprintf("templates/svgs/%s", basename)
		name := strings.TrimSuffix(basename, filepath.Ext(basename))

		b, _ := api.Assets.ReadFile(path)
		baseTemplate = template.Must(baseTemplate.New("svg/" + name).Parse(string(b)))
		templates["svg/"+name] = baseTemplate
	}

	// Load Components
	components, _ := api.Assets.ReadDir("templates/components")
	for _, item := range components {
		basename := item.Name()
		path := fmt.Sprintf("templates/components/%s", basename)
		name := strings.TrimSuffix(basename, filepath.Ext(basename))

		// Clone Base Template
		b, _ := api.Assets.ReadFile(path)
		baseTemplate = template.Must(baseTemplate.New("component/" + name).Parse(string(b)))
		render.Add("component/"+name, baseTemplate)
		templates["component/"+name] = baseTemplate
	}

	// Load Pages
	pages, _ := api.Assets.ReadDir("templates/pages")
	for _, item := range pages {
		basename := item.Name()
		path := fmt.Sprintf("templates/pages/%s", basename)
		name := strings.TrimSuffix(basename, filepath.Ext(basename))

		// Clone Base Template
		b, _ := api.Assets.ReadFile(path)
		pageTemplate, _ := template.Must(baseTemplate.Clone()).New("page/" + name).Parse(string(b))
		render.Add("page/"+name, pageTemplate)
		templates["page/"+name] = pageTemplate
	}

	api.Templates = templates

	return &render
}

func generateToken(n int) ([]byte, error) {
	b := make([]byte, n)
	_, err := rand.Read(b)
	if err != nil {
		return nil, err
	}
	return b, nil
}