/*
		GNU GENERAL PUBLIC LICENSE
                 Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

 http-wokou, An HTTP Proxying framework for bypassing DNS Security
 Copyright (C) 2024 Russell Hrubesky, ChiralWorks Software LLC

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.

*/

package httpserver

import (
	"fmt"
	"log"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"os"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/patrickmn/go-cache"
	"golang.org/x/net/publicsuffix"
)

// Implementing a 'set'
var NonmutableHeaders = map[string]struct{}{
	"Cookie":          struct{}{},
	"User-Agent":      struct{}{},
	"Accept-Encoding": struct{}{},
	"Referer":         struct{}{},
	"X-Proxy-Url":     struct{}{},
	"Host":            struct{}{},
}

type TokenUpdate struct {
	Code    string `form:"code"`
	Content string `form:"content"`
}

type Controller struct {
	Config    *HttpServerConfig
	RouteMaps *RouteMap
	PageMods  *AllPageMods
	Client    *http.Client
	SiteUrl   *url.URL
	cache     *cache.Cache
}

type ProxyCookies struct {
	ck map[*url.URL][]*http.Cookie
}

/*
Returns a new Controller struct to register routes to the gin router

	:param cfg: A pointer to an HttpServerConfig struct
*/
func NewController(cfg *HttpServerConfig, routeMap *RouteMap) *Controller {

	jar, err := cookiejar.New(&cookiejar.Options{PublicSuffixList: publicsuffix.List})
	if err != nil {
		log.Fatal(err)
	}

	sessCookies := cfg.CookieJar
	domain, err := url.Parse(cfg.FullDomain)
	if err != nil {
		log.Fatal(err)
	}
	pgMod := LoadPageMods(cfg.PageModPath)
	jar.SetCookies(domain, sessCookies)

	var resCache *cache.Cache
	if cfg.Caching {
		fmt.Printf("Starting server with resource caching ENABLED.\n")
		resCache = cache.New(24*time.Hour, 10*time.Minute)
	} else {
		fmt.Printf("Starting server with resource caching DISABLED.\n")
		resCache = nil
	}
	return &Controller{Config: cfg, Client: &http.Client{Jar: jar, CheckRedirect: func(req *http.Request, via []*http.Request) error { return http.ErrUseLastResponse }},
		SiteUrl: domain, cache: resCache, RouteMaps: routeMap, PageMods: pgMod}
}

/*
This handler will be responsible for proxying out the GET requests that the server recieves
*/
func (c *Controller) HandleAny(ctx *gin.Context) {
	incomingPath := ctx.Param("ProxiedPath")
	for idx := range c.Config.Redirects {
		if incomingPath == c.Config.Redirects[idx].From {
			ctx.Header("Location", c.Config.Redirects[idx].To)
			ctx.Status(302)
			return
		}
	}
	if incomingPath == "/update" {
		if ctx.Request.Method == "POST" {
			c.UpdatePost(ctx)
			return
		}
	}
	if c.Config.CustomFserve != nil {
		for idx := range c.Config.CustomFserve.Config {
			if incomingPath == c.Config.CustomFserve.Config[idx].Request {
				fmt.Print("Custom file server path hit.\n")
				ctx.Data(200, c.Config.CustomFserve.Config[idx].ContentType, c.Config.CustomFserve.Config[idx].FileData)
				return
			}
		}
	}
	if c.Config.Caching {
		cacheHit := c.GetResource(incomingPath)
		if cacheHit != nil {
			for k, v := range *cacheHit.Headers {
				_, ok := NonmutableHeaders[k]
				if !ok {
					for i := range v {
						ctx.Header(k, v[i])
					}
				}
			}
			ctx.Data(cacheHit.Rcode, cacheHit.Headers.Get("content-type"), cacheHit.Data)
			return
		} else {
			fmt.Printf("Cache MISS! For resource URI: %s\n", incomingPath)
		}
	}

	dname, ok := c.RouteMaps.GetMappedDomain(incomingPath)
	if ok { // below, RequestURI() returns the whole URI with the query
		data, headers, rcode, err := c.RequestGeneric(ctx.Request.Method, dname, ctx.Request.URL.RequestURI(), &ctx.Request.Header, ctx.Request.Body)
		if err != nil {
			log.Fatal(err, " failed to route the request: ", incomingPath, " to the target domain: ", dname, " Error: ", err)
		}
		for k, v := range *headers {
			_, ok := NonmutableHeaders[k]
			if !ok {
				ctx.Header(k, v[0])
			}
		}
		ctx.Header("access-control-allow-origin", c.Config.FullProxyDomain)
		ctx.Data(rcode, headers.Get("content-type"), data)
		return
	}

	c.TryHosts(ctx.Request.Method, ctx.Request.URL.RequestURI(), &ctx.Request.Header, ctx.Request.Body, c.Config.KnownHosts)
}

/*
This function handles the updating of cookie values, meant to be extendable down the road //  TODO: Make this more configurable

	:param ctx: pointer to a gin Context struct
*/
func (c *Controller) UpdatePost(ctx *gin.Context) {
	tk := TokenUpdate{
		Code:    ctx.PostForm("code"),
		Content: ctx.PostForm("content"),
	}

	if tk.Code != c.Config.TkUpdateCode {
		ctx.JSON(401, map[string]string{
			"msg": "UNAUTHORIZED",
		})
		return
	}
	err := os.WriteFile(c.Config.TokenSaveLoc, []byte(tk.Content), os.ModePerm)
	if err != nil {
		ctx.JSON(500, map[string]string{
			"Error": fmt.Sprintf("couldnt write token to disk. Error: %s", err),
		})
		return
	}
	ctx.String(200, "Token updated.")

}