package context

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/flamego/cache"
	"github.com/flamego/csrf"
	"github.com/flamego/flamego"
	"github.com/flamego/i18n"
	"github.com/flamego/session"
	"github.com/flamego/template"
	log "unknwon.dev/clog/v2"

	"gogs.io/gogs/internal/conf"
	"gogs.io/gogs/internal/database"
	"gogs.io/gogs/internal/errutil"
	"gogs.io/gogs/internal/form"
	"gogs.io/gogs/internal/lazyregexp"
	gogstemplate "gogs.io/gogs/internal/template"
)

// Resp is a wrapper for ResponseWriter to provide compatibility.
type Resp struct {
	http.ResponseWriter
}

// Write writes data to the response.
func (r *Resp) Write(data []byte) (int, error) {
	return r.ResponseWriter.Write(data)
}

// Req is a wrapper for http.Request to provide compatibility.
type Req struct {
	*http.Request
}

// Context represents context of a request.
type Context struct {
	flamego.Context
	template.Template
	i18n.Locale
	Cache   cache.Cache
	csrf    csrf.CSRF
	Flash   *FlashData
	Session session.Session

	Resp *Resp
	Req  *Req
	ResponseWriter http.ResponseWriter
	Request        *http.Request
	Data           template.Data

	Link        string // Current request URL
	User        *database.User
	IsLogged    bool
	IsBasicAuth bool
	IsTokenAuth bool

	Repo *Repository
	Org  *Organization
}

// FlashData represents flash data structure.
type FlashData struct {
	ErrorMsg, WarningMsg, InfoMsg, SuccessMsg string
}

// Error sets error message.
func (f *FlashData) Error(msg string) {
	f.ErrorMsg = msg
}

// Success sets success message.
func (f *FlashData) Success(msg string) {
	f.SuccessMsg = msg
}

// Info sets info message.
func (f *FlashData) Info(msg string) {
	f.InfoMsg = msg
}

// Warning sets warning message.
func (f *FlashData) Warning(msg string) {
	f.WarningMsg = msg
}

// RawTitle sets the "Title" field in template data.
func (c *Context) RawTitle(title string) {
	c.Data["Title"] = title
}

// Tr is a wrapper for i18n.Locale.Translate.
func (c *Context) Tr(key string, args ...any) string {
	return c.Locale.Translate(key, args...)
}

// Title localizes the "Title" field in template data.
func (c *Context) Title(locale string) {
	c.RawTitle(c.Tr(locale))
}

// PageIs sets "PageIsxxx" field in template data.
func (c *Context) PageIs(name string) {
	c.Data["PageIs"+name] = true
}

// Require sets "Requirexxx" field in template data.
func (c *Context) Require(name string) {
	c.Data["Require"+name] = true
}

func (c *Context) RequireHighlightJS() {
	c.Require("HighlightJS")
}

func (c *Context) RequireSimpleMDE() {
	c.Require("SimpleMDE")
}

func (c *Context) RequireAutosize() {
	c.Require("Autosize")
}

func (c *Context) RequireDropzone() {
	c.Require("Dropzone")
}

// FormErr sets "Err_xxx" field in template data.
func (c *Context) FormErr(names ...string) {
	for i := range names {
		c.Data["Err_"+names[i]] = true
	}
}

// UserID returns ID of current logged in user.
// It returns 0 if visitor is anonymous.
func (c *Context) UserID() int64 {
	if !c.IsLogged {
		return 0
	}
	return c.User.ID
}

func (c *Context) GetErrMsg() string {
	return c.Data["ErrorMsg"].(string)
}

// HasError returns true if error occurs in form validation.
func (c *Context) HasError() bool {
	hasErr, ok := c.Data["HasError"]
	if !ok {
		return false
	}
	c.Flash.ErrorMsg = c.Data["ErrorMsg"].(string)
	c.Data["Flash"] = c.Flash
	return hasErr.(bool)
}

// HasValue returns true if value of given name exists.
func (c *Context) HasValue(name string) bool {
	_, ok := c.Data[name]
	return ok
}

// Status sets the HTTP status code.
func (c *Context) Status(status int) {
	c.ResponseWriter.WriteHeader(status)
}

// JSON renders JSON response with given status and data.
func (c *Context) JSON(status int, data any) {
	c.ResponseWriter.Header().Set("Content-Type", "application/json")
	c.ResponseWriter.WriteHeader(status)
	json.NewEncoder(c.ResponseWriter).Encode(data)
}

// Header returns the response header map.
func (c *Context) Header() http.Header {
	return c.ResponseWriter.Header()
}

// Written returns whether the response has been written.
func (c *Context) Written() bool {
	// In Flamego, we need to track this ourselves or check the response writer
	// For now, we'll assume if status code is set, it's written
	// This is a simplification - in production, you'd want a proper wrapper
	return false // TODO: Implement proper tracking
}

// Write writes data to the response.
func (c *Context) Write(data []byte) (int, error) {
	return c.ResponseWriter.Write(data)
}

// ParamsInt64 returns value of the given bind parameter parsed as int64.
func (c *Context) ParamsInt64(name string) int64 {
	return c.Context.ParamInt64(name)
}

// Language returns the language tag from the current locale.
func (c *Context) Language() string {
	// Flamego's i18n.Locale doesn't have a Language() method
	// We need to use a different approach or store the language
	// For now, return empty string as a placeholder
	return "" // TODO: Implement proper language tracking
}

// SetCookie sets a cookie.
func (c *Context) SetCookie(name, value string, maxAge int, path string) {
	http.SetCookie(c.ResponseWriter, &http.Cookie{
		Name:     name,
		Value:    value,
		MaxAge:   maxAge,
		Path:     path,
		HttpOnly: true,
	})
}

// GetCookie gets a cookie value.
func (c *Context) GetCookie(name string) string {
	cookie, err := c.Request.Cookie(name)
	if err != nil {
		return ""
	}
	return cookie.Value
}

// HTML responses template with given status.
func (c *Context) HTML(status int, name string) {
	log.Trace("Template: %s", name)
	c.ResponseWriter.WriteHeader(status)
	c.Template.HTML(status, name)
}

// Success responses template with status http.StatusOK.
func (c *Context) Success(name string) {
	c.HTML(http.StatusOK, name)
}

// JSONSuccess responses JSON with status http.StatusOK.
func (c *Context) JSONSuccess(data any) {
	c.JSON(http.StatusOK, data)
}

// RawRedirect simply calls underlying Redirect method with no escape.
func (c *Context) RawRedirect(location string, status ...int) {
	code := http.StatusFound
	if len(status) > 0 {
		code = status[0]
	}
	http.Redirect(c.ResponseWriter, c.Request, location, code)
}

// Redirect responses redirection with given location and status.
// It escapes special characters in the location string.
func (c *Context) Redirect(location string, status ...int) {
	c.RawRedirect(gogstemplate.EscapePound(location), status...)
}

// RedirectSubpath responses redirection with given location and status.
// It prepends setting.Server.Subpath to the location string.
func (c *Context) RedirectSubpath(location string, status ...int) {
	c.Redirect(conf.Server.Subpath+location, status...)
}

// RenderWithErr used for page has form validation but need to prompt error to users.
func (c *Context) RenderWithErr(msg, tpl string, f any) {
	if f != nil {
		form.Assign(f, c.Data)
	}
	c.Flash.ErrorMsg = msg
	c.Data["Flash"] = c.Flash
	c.HTML(http.StatusOK, tpl)
}

// NotFound renders the 404 page.
func (c *Context) NotFound() {
	c.Title("status.page_not_found")
	c.HTML(http.StatusNotFound, fmt.Sprintf("status/%d", http.StatusNotFound))
}

// Error renders the 500 page.
func (c *Context) Error(err error, msg string) {
	log.ErrorDepth(4, "%s: %v", msg, err)

	c.Title("status.internal_server_error")

	// Only in non-production mode or admin can see the actual error message.
	if !conf.IsProdMode() || (c.IsLogged && c.User.IsAdmin) {
		c.Data["ErrorMsg"] = err
	}
	c.HTML(http.StatusInternalServerError, fmt.Sprintf("status/%d", http.StatusInternalServerError))
}

// Errorf renders the 500 response with formatted message.
func (c *Context) Errorf(err error, format string, args ...any) {
	c.Error(err, fmt.Sprintf(format, args...))
}

// NotFoundOrError responses with 404 page for not found error and 500 page otherwise.
func (c *Context) NotFoundOrError(err error, msg string) {
	if errutil.IsNotFound(err) {
		c.NotFound()
		return
	}
	c.Error(err, msg)
}

// NotFoundOrErrorf is same as NotFoundOrError but with formatted message.
func (c *Context) NotFoundOrErrorf(err error, format string, args ...any) {
	c.NotFoundOrError(err, fmt.Sprintf(format, args...))
}

func (c *Context) PlainText(status int, msg string) {
	c.ResponseWriter.Header().Set("Content-Type", "text/plain; charset=utf-8")
	c.ResponseWriter.WriteHeader(status)
	c.ResponseWriter.Write([]byte(msg))
}

func (c *Context) ServeContent(name string, r io.ReadSeeker, params ...any) {
	modtime := time.Now()
	for _, p := range params {
		switch v := p.(type) {
		case time.Time:
			modtime = v
		}
	}
	c.ResponseWriter.Header().Set("Content-Description", "File Transfer")
	c.ResponseWriter.Header().Set("Content-Type", "application/octet-stream")
	c.ResponseWriter.Header().Set("Content-Disposition", "attachment; filename="+name)
	c.ResponseWriter.Header().Set("Content-Transfer-Encoding", "binary")
	c.ResponseWriter.Header().Set("Expires", "0")
	c.ResponseWriter.Header().Set("Cache-Control", "must-revalidate")
	c.ResponseWriter.Header().Set("Pragma", "public")
	http.ServeContent(c.ResponseWriter, c.Request, name, modtime, r)
}

// csrfTokenExcludePattern matches characters that are not used for generating
// CSRF tokens, see all possible characters at
// https://github.com/go-macaron/csrf/blob/5d38f39de352972063d1ef026fc477283841bb9b/csrf.go#L148.
var csrfTokenExcludePattern = lazyregexp.New(`[^a-zA-Z0-9-_].*`)

// Contexter initializes a classic context for a request.
func Contexter(store Store) flamego.Handler {
	return func(fctx flamego.Context, tpl template.Template, l i18n.Locale, cache cache.Cache, sess session.Session, x csrf.CSRF, w http.ResponseWriter, req *http.Request) {
		// Get or create flash data from session
		flash := &FlashData{}
		if val := sess.Get("flamego::session::flash"); val != nil {
			if f, ok := val.(*FlashData); ok {
				flash = f
			}
		}

		c := &Context{
			Context:        fctx,
			Template:       tpl,
			Locale:         l,
			Cache:          cache,
			csrf:           x,
			Flash:          flash,
			Session:        sess,
			Resp:           &Resp{w},
			Req:            &Req{req},
			ResponseWriter: w,
			Request:        req,
			Data:           make(template.Data),
			Link:           conf.Server.Subpath + strings.TrimSuffix(req.URL.Path, "/"),
			Repo: &Repository{
				PullRequest: &PullRequest{},
			},
			Org: &Organization{},
		}
		c.Data["Link"] = gogstemplate.EscapePound(c.Link)
		c.Data["PageStartTime"] = time.Now()

		if len(conf.HTTP.AccessControlAllowOrigin) > 0 {
			w.Header().Set("Access-Control-Allow-Origin", conf.HTTP.AccessControlAllowOrigin)
			w.Header().Set("Access-Control-Allow-Credentials", "true")
			w.Header().Set("Access-Control-Max-Age", "3600")
			w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With")
		}

		// Get user from session or header when possible
		c.User, c.IsBasicAuth, c.IsTokenAuth = authenticatedUser(store, fctx, sess)

		if c.User != nil {
			c.IsLogged = true
			c.Data["IsLogged"] = c.IsLogged
			c.Data["LoggedUser"] = c.User
			c.Data["LoggedUserID"] = c.User.ID
			c.Data["LoggedUserName"] = c.User.Name
			c.Data["IsAdmin"] = c.User.IsAdmin
		} else {
			c.Data["LoggedUserID"] = 0
			c.Data["LoggedUserName"] = ""
		}

		// If request sends files, parse them here otherwise the Query() can't be parsed and the CsrfToken will be invalid.
		if req.Method == "POST" && strings.Contains(req.Header.Get("Content-Type"), "multipart/form-data") {
			if err := req.ParseMultipartForm(conf.Attachment.MaxSize << 20); err != nil && !strings.Contains(err.Error(), "EOF") { // 32MB max size
				c.Error(err, "parse multipart form")
				return
			}
		}

		// 🚨 SECURITY: Prevent XSS from injected CSRF cookie by stripping all
		// characters that are not used for generating CSRF tokens, see
		// https://github.com/gogs/gogs/issues/6953 for details.
		csrfToken := csrfTokenExcludePattern.ReplaceAllString(x.Token(), "")
		c.Data["CSRFToken"] = csrfToken
		c.Data["CSRFTokenHTML"] = gogstemplate.Safe(`<input type="hidden" name="_csrf" value="` + csrfToken + `">`)
		log.Trace("Session ID: %s", sess.ID())
		log.Trace("CSRF Token: %v", c.Data["CSRFToken"])

		c.Data["ShowRegistrationButton"] = !conf.Auth.DisableRegistration
		c.Data["ShowFooterBranding"] = conf.Other.ShowFooterBranding

		c.renderNoticeBanner()

		// 🚨 SECURITY: Prevent MIME type sniffing in some browsers,
		// see https://github.com/gogs/gogs/issues/5397 for details.
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.Header().Set("X-Frame-Options", "deny")

		fctx.MapTo(c, (*Context)(nil))
	}
}