// Beego (http://beego.me/)
// @description beego is an open-source, high-performance web framework for the Go programming language.
// @link        http://github.com/astaxie/beego for the canonical source repository
// @license     http://github.com/astaxie/beego/blob/master/LICENSE
// @authors     astaxie

package context

import (
	"bytes"
	"compress/flate"
	"compress/gzip"
	"encoding/json"
	"encoding/xml"
	"errors"
	"fmt"
	"html/template"
	"io"
	"mime"
	"net/http"
	"path/filepath"
	"strconv"
	"strings"
)

// BeegoOutput does work for sending response header.
type BeegoOutput struct {
	Context    *Context
	Status     int
	EnableGzip bool
}

// NewOutput returns new BeegoOutput.
// it contains nothing now.
func NewOutput() *BeegoOutput {
	return &BeegoOutput{}
}

// Header sets response header item string via given key.
func (output *BeegoOutput) Header(key, val string) {
	output.Context.ResponseWriter.Header().Set(key, val)
}

// Body sets response body content.
// if EnableGzip, compress content string.
// it sends out response body directly.
func (output *BeegoOutput) Body(content []byte) {
	output_writer := output.Context.ResponseWriter.(io.Writer)
	if output.EnableGzip == true && output.Context.Input.Header("Accept-Encoding") != "" {
		splitted := strings.SplitN(output.Context.Input.Header("Accept-Encoding"), ",", -1)
		encodings := make([]string, len(splitted))

		for i, val := range splitted {
			encodings[i] = strings.TrimSpace(val)
		}
		for _, val := range encodings {
			if val == "gzip" {
				output.Header("Content-Encoding", "gzip")
				output_writer, _ = gzip.NewWriterLevel(output.Context.ResponseWriter, gzip.BestSpeed)

				break
			} else if val == "deflate" {
				output.Header("Content-Encoding", "deflate")
				output_writer, _ = flate.NewWriter(output.Context.ResponseWriter, flate.BestSpeed)
				break
			}
		}
	} else {
		output.Header("Content-Length", strconv.Itoa(len(content)))
	}
	output_writer.Write(content)
	switch output_writer.(type) {
	case *gzip.Writer:
		output_writer.(*gzip.Writer).Close()
	case *flate.Writer:
		output_writer.(*flate.Writer).Close()
	}
}

// Cookie sets cookie value via given key.
// others are ordered as cookie's max age time, path,domain, secure and httponly.
func (output *BeegoOutput) Cookie(name string, value string, others ...interface{}) {
	var b bytes.Buffer
	fmt.Fprintf(&b, "%s=%s", sanitizeName(name), sanitizeValue(value))
	if len(others) > 0 {
		switch v := others[0].(type) {
		case int:
			if v > 0 {
				fmt.Fprintf(&b, "; Max-Age=%d", v)
			} else if v < 0 {
				fmt.Fprintf(&b, "; Max-Age=0")
			}
		case int64:
			if v > 0 {
				fmt.Fprintf(&b, "; Max-Age=%d", v)
			} else if v < 0 {
				fmt.Fprintf(&b, "; Max-Age=0")
			}
		case int32:
			if v > 0 {
				fmt.Fprintf(&b, "; Max-Age=%d", v)
			} else if v < 0 {
				fmt.Fprintf(&b, "; Max-Age=0")
			}
		}
	}

	// the settings below
	// Path, Domain, Secure, HttpOnly
	// can use nil skip set

	// default "/"
	if len(others) > 1 {
		if v, ok := others[1].(string); ok && len(v) > 0 {
			fmt.Fprintf(&b, "; Path=%s", sanitizeValue(v))
		}
	} else {
		fmt.Fprintf(&b, "; Path=%s", "/")
	}

	// default empty
	if len(others) > 2 {
		if v, ok := others[2].(string); ok && len(v) > 0 {
			fmt.Fprintf(&b, "; Domain=%s", sanitizeValue(v))
		}
	}

	// default empty
	if len(others) > 3 {
		var secure bool
		switch v := others[3].(type) {
		case bool:
			secure = v
		default:
			if others[3] != nil {
				secure = true
			}
		}
		if secure {
			fmt.Fprintf(&b, "; Secure")
		}
	}

	// default false. for session cookie default true
	httponly := false
	if len(others) > 4 {
		if v, ok := others[4].(bool); ok && v {
			// HttpOnly = true
			httponly = true
		}
	}

	if httponly {
		fmt.Fprintf(&b, "; HttpOnly")
	}

	output.Context.ResponseWriter.Header().Add("Set-Cookie", b.String())
}

var cookieNameSanitizer = strings.NewReplacer("\n", "-", "\r", "-")

func sanitizeName(n string) string {
	return cookieNameSanitizer.Replace(n)
}

var cookieValueSanitizer = strings.NewReplacer("\n", " ", "\r", " ", ";", " ")

func sanitizeValue(v string) string {
	return cookieValueSanitizer.Replace(v)
}

// Json writes json to response body.
// if coding is true, it converts utf-8 to \u0000 type.
func (output *BeegoOutput) Json(data interface{}, hasIndent bool, coding bool) error {
	output.Header("Content-Type", "application/json;charset=UTF-8")
	var content []byte
	var err error
	if hasIndent {
		content, err = json.MarshalIndent(data, "", "  ")
	} else {
		content, err = json.Marshal(data)
	}
	if err != nil {
		http.Error(output.Context.ResponseWriter, err.Error(), http.StatusInternalServerError)
		return err
	}
	if coding {
		content = []byte(stringsToJson(string(content)))
	}
	output.Body(content)
	return nil
}

// Jsonp writes jsonp to response body.
func (output *BeegoOutput) Jsonp(data interface{}, hasIndent bool) error {
	output.Header("Content-Type", "application/javascript;charset=UTF-8")
	var content []byte
	var err error
	if hasIndent {
		content, err = json.MarshalIndent(data, "", "  ")
	} else {
		content, err = json.Marshal(data)
	}
	if err != nil {
		http.Error(output.Context.ResponseWriter, err.Error(), http.StatusInternalServerError)
		return err
	}
	callback := output.Context.Input.Query("callback")
	if callback == "" {
		return errors.New(`"callback" parameter required`)
	}
	callback_content := bytes.NewBufferString(" " + template.JSEscapeString(callback))
	callback_content.WriteString("(")
	callback_content.Write(content)
	callback_content.WriteString(");\r\n")
	output.Body(callback_content.Bytes())
	return nil
}

// Xml writes xml string to response body.
func (output *BeegoOutput) Xml(data interface{}, hasIndent bool) error {
	output.Header("Content-Type", "application/xml;charset=UTF-8")
	var content []byte
	var err error
	if hasIndent {
		content, err = xml.MarshalIndent(data, "", "  ")
	} else {
		content, err = xml.Marshal(data)
	}
	if err != nil {
		http.Error(output.Context.ResponseWriter, err.Error(), http.StatusInternalServerError)
		return err
	}
	output.Body(content)
	return nil
}

// Download forces response for download file.
// it prepares the download response header automatically.
func (output *BeegoOutput) Download(file string) {
	output.Header("Content-Description", "File Transfer")
	output.Header("Content-Type", "application/octet-stream")
	output.Header("Content-Disposition", "attachment; filename="+filepath.Base(file))
	output.Header("Content-Transfer-Encoding", "binary")
	output.Header("Expires", "0")
	output.Header("Cache-Control", "must-revalidate")
	output.Header("Pragma", "public")
	http.ServeFile(output.Context.ResponseWriter, output.Context.Request, file)
}

// ContentType sets the content type from ext string.
// MIME type is given in mime package.
func (output *BeegoOutput) ContentType(ext string) {
	if !strings.HasPrefix(ext, ".") {
		ext = "." + ext
	}
	ctype := mime.TypeByExtension(ext)
	if ctype != "" {
		output.Header("Content-Type", ctype)
	}
}

// SetStatus sets response status code.
// It writes response header directly.
func (output *BeegoOutput) SetStatus(status int) {
	output.Context.ResponseWriter.WriteHeader(status)
	output.Status = status
}

// IsCachable returns boolean of this request is cached.
// HTTP 304 means cached.
func (output *BeegoOutput) IsCachable(status int) bool {
	return output.Status >= 200 && output.Status < 300 || output.Status == 304
}

// IsEmpty returns boolean of this request is empty.
// HTTP 201，204 and 304 means empty.
func (output *BeegoOutput) IsEmpty(status int) bool {
	return output.Status == 201 || output.Status == 204 || output.Status == 304
}

// IsOk returns boolean of this request runs well.
// HTTP 200 means ok.
func (output *BeegoOutput) IsOk(status int) bool {
	return output.Status == 200
}

// IsSuccessful returns boolean of this request runs successfully.
// HTTP 2xx means ok.
func (output *BeegoOutput) IsSuccessful(status int) bool {
	return output.Status >= 200 && output.Status < 300
}

// IsRedirect returns boolean of this request is redirection header.
// HTTP 301,302,307 means redirection.
func (output *BeegoOutput) IsRedirect(status int) bool {
	return output.Status == 301 || output.Status == 302 || output.Status == 303 || output.Status == 307
}

// IsForbidden returns boolean of this request is forbidden.
// HTTP 403 means forbidden.
func (output *BeegoOutput) IsForbidden(status int) bool {
	return output.Status == 403
}

// IsNotFound returns boolean of this request is not found.
// HTTP 404 means forbidden.
func (output *BeegoOutput) IsNotFound(status int) bool {
	return output.Status == 404
}

// IsClient returns boolean of this request client sends error data.
// HTTP 4xx means forbidden.
func (output *BeegoOutput) IsClientError(status int) bool {
	return output.Status >= 400 && output.Status < 500
}

// IsServerError returns boolean of this server handler errors.
// HTTP 5xx means server internal error.
func (output *BeegoOutput) IsServerError(status int) bool {
	return output.Status >= 500 && output.Status < 600
}

func stringsToJson(str string) string {
	rs := []rune(str)
	jsons := ""
	for _, r := range rs {
		rint := int(r)
		if rint < 128 {
			jsons += string(r)
		} else {
			jsons += "\\u" + strconv.FormatInt(int64(rint), 16) // json
		}
	}
	return jsons
}

// Sessions sets session item value with given key.
func (output *BeegoOutput) Session(name interface{}, value interface{}) {
	output.Context.Input.CruSession.Set(name, value)
}