/*
* @Author: Bartuccio Antoine
* @Date:   2018-07-14 11:32:11
* @Last Modified by:   klmp200
* @Last Modified time: 2018-07-18 20:06:08
 */

package gowebframework

import (
	"encoding/json"
	"fmt"
	"github.com/oxtoacart/bpool"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"path/filepath"
	"time"
)

var templates map[string]*template.Template
var buffer_pool *bpool.BufferPool

type Config struct {
	TemplateIncludePath      string
	TemplateLayoutPath       string
	MainTemplate             string
	StaticFolderPath         string
	TemplateExtensionPattern string
	ServerPort               string
	ServerListenAddress      string
	SessionProvider          string
	Domain                   string
	Debug                    bool
}

var ServerConfig Config

// Load templates and configuration
func Configure(config_file_name string, custom_config_file_name string) {
	loadConfiguration(config_file_name, custom_config_file_name)
	loadTemplates()
	// initialise sessions
	SessionProviderRegister(FileSessionProvider{}, "FileProvider")
	// Put a session of 1 day duration
	ses, err := newSessionManager(ServerConfig.SessionProvider, "GOSESSID", time.Hour*24)
	if err != nil {
		log.Fatal(err)
	}
	SESSION = ses
	go clearExpiredSessionsCron()
}

// Starts server
func Start() {
	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir(ServerConfig.StaticFolderPath))))
	log.Println("Server listening on http://" + ServerConfig.ServerListenAddress + ":" + ServerConfig.ServerPort)
	log.Fatal(http.ListenAndServe(ServerConfig.ServerListenAddress+":"+ServerConfig.ServerPort, nil))
}

func loadDefaultConfiguration() {
	ServerConfig.StaticFolderPath = "statics/"
	ServerConfig.TemplateIncludePath = "templates/"
	ServerConfig.TemplateLayoutPath = "templates/layouts/"
	ServerConfig.TemplateExtensionPattern = "*.gohtml"
	ServerConfig.ServerPort = "8000"
	ServerConfig.ServerListenAddress = "0.0.0.0"
	ServerConfig.Domain = "localhost"
	ServerConfig.MainTemplate = `{{define "main" }} {{ template "base" . }} {{ end }}`
	ServerConfig.Debug = false
	ServerConfig.SessionProvider = "FileProvider"
}

func loadConfiguration(config_file_name string, custom_config_file_name string) {
	loadDefaultConfiguration()
	default_settings, err := ioutil.ReadFile(config_file_name)
	if err != nil {
		log.Println("No " + config_file_name + " found, using default conf instead")
	} else {
		log.Println("Importing settings")
		err = json.Unmarshal(default_settings, &ServerConfig)
		if err != nil {
			log.Fatal("Malformed " + config_file_name)
		}
	}

	custom_settings, err := ioutil.ReadFile(custom_config_file_name)
	if err != nil {
		log.Println("No settings_custom.json fonud, skipping")
		return
	}
	log.Println("Importing custom settings")
	err = json.Unmarshal(custom_settings, &ServerConfig)
	if err != nil {
		log.Fatal("Malformed " + custom_config_file_name)
	}
}

func loadTemplates() {
	if templates == nil {
		templates = make(map[string]*template.Template)
	}

	layoutFiles, err := filepath.Glob(ServerConfig.TemplateLayoutPath + ServerConfig.TemplateExtensionPattern)
	if err != nil {
		log.Fatal(err)
	}

	includeFiles, err := filepath.Glob(ServerConfig.TemplateIncludePath + ServerConfig.TemplateExtensionPattern)
	if err != nil {
		log.Fatal(err)
	}

	mainTemplate := template.New("main")
	mainTemplate, err = mainTemplate.Parse(ServerConfig.MainTemplate)

	for _, file := range includeFiles {
		fileName := filepath.Base(file)
		log.Println("Loading template", fileName)
		files := append(layoutFiles, file)
		templates[fileName], err = mainTemplate.Clone()
		if err != nil {
			log.Fatal(err)
		}
		templates[fileName] = template.Must(templates[fileName].ParseFiles(files...))
	}
	log.Println("Templates loading successful")
	buffer_pool = bpool.NewBufferPool(64)
	log.Println("Buffer allocation sucessful")
}

// Renders a template loaded. It allows templat "inheritance" and pass data into it
// Automatic reload if debug mode is enabled
func RenderTemplate(w http.ResponseWriter, name string, data interface{}) {
	if ServerConfig.Debug {
		loadTemplates()
	}

	tmpl, is_ok := templates[name]
	if !is_ok {
		http.Error(w, fmt.Sprintf("The template %s does not exist.", name),
			http.StatusInternalServerError)
	}
	buf := buffer_pool.Get()
	defer buffer_pool.Put(buf)

	err := tmpl.Execute(buf, data)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	buf.WriteTo(w)
}