package rest

import (
	"github.com/kataras/iris/config"
	"github.com/kataras/iris/utils"
	"github.com/microcosm-cc/bluemonday"
	"github.com/russross/blackfriday"
	"github.com/valyala/fasthttp"
)

const (
	// ContentBinary header value for binary data.
	ContentBinary = "application/octet-stream"
	// ContentJSON header value for JSON data.
	ContentJSON = "application/json"
	// ContentJSONP header value for JSONP data.
	ContentJSONP = "application/javascript"
	// ContentLength header constant.
	ContentLength = "Content-Length"
	// ContentText header value for Text data.
	ContentText = "text/plain"
	// ContentType header constant.
	ContentType = "Content-Type"
	// ContentXML header value for XML data.
	ContentXML = "text/xml"
)

// bufPool represents a reusable buffer pool for executing templates into.
var bufPool *utils.BufferPool

// Render is a service that provides functions for easily writing JSON, XML,
// binary data, and HTML templates out to a HTTP Response.
type Render struct {
	// Customize Secure with an Options struct.
	Config          config.Rest
	CompiledCharset string
}

// New constructs a new Render instance with the supplied configs.
func New(cfg ...config.Rest) *Render {
	if bufPool == nil {
		bufPool = utils.NewBufferPool(64)
	}

	c := config.DefaultRest().Merge(cfg)

	r := &Render{
		Config: c,
	}

	r.prepareConfig()

	return r
}

func (r *Render) prepareConfig() {
	// Fill in the defaults if need be.
	if len(r.Config.Charset) == 0 {
		r.Config.Charset = config.Charset
	}
	r.CompiledCharset = "; charset=" + r.Config.Charset
}

// Render is the generic function called by XML, JSON, Data, HTML, and can be called by custom implementations.
func (r *Render) Render(ctx *fasthttp.RequestCtx, e Engine, data interface{}) error {
	var err error
	if r.Config.Gzip {
		err = e.RenderGzip(ctx, data)
	} else {
		err = e.Render(ctx, data)
	}

	if err != nil && !r.Config.DisableHTTPErrorRendering {
		ctx.Response.SetBodyString(err.Error())
		ctx.Response.SetStatusCode(fasthttp.StatusInternalServerError)
	}
	return err
}

// Data writes out the raw bytes as binary data.
func (r *Render) Data(ctx *fasthttp.RequestCtx, status int, v []byte) error {
	head := Head{
		ContentType: ContentBinary,
		Status:      status,
	}

	d := Data{
		Head: head,
	}

	return r.Render(ctx, d, v)
}

// JSON marshals the given interface object and writes the JSON response.
func (r *Render) JSON(ctx *fasthttp.RequestCtx, status int, v interface{}) error {
	head := Head{
		ContentType: ContentJSON + r.CompiledCharset,
		Status:      status,
	}

	j := JSON{
		Head:          head,
		Indent:        r.Config.IndentJSON,
		Prefix:        r.Config.PrefixJSON,
		UnEscapeHTML:  r.Config.UnEscapeHTML,
		StreamingJSON: r.Config.StreamingJSON,
	}

	return r.Render(ctx, j, v)
}

// JSONP marshals the given interface object and writes the JSON response.
func (r *Render) JSONP(ctx *fasthttp.RequestCtx, status int, callback string, v interface{}) error {
	head := Head{
		ContentType: ContentJSONP + r.CompiledCharset,
		Status:      status,
	}

	j := JSONP{
		Head:     head,
		Indent:   r.Config.IndentJSON,
		Callback: callback,
	}

	return r.Render(ctx, j, v)
}

// Text writes out a string as plain text.
func (r *Render) Text(ctx *fasthttp.RequestCtx, status int, v string) error {
	head := Head{
		ContentType: ContentText + r.CompiledCharset,
		Status:      status,
	}

	t := Text{
		Head: head,
	}

	return r.Render(ctx, t, v)
}

// XML marshals the given interface object and writes the XML response.
func (r *Render) XML(ctx *fasthttp.RequestCtx, status int, v interface{}) error {
	head := Head{
		ContentType: ContentXML + r.CompiledCharset,
		Status:      status,
	}

	x := XML{
		Head:   head,
		Indent: r.Config.IndentXML,
		Prefix: r.Config.PrefixXML,
	}

	return r.Render(ctx, x, v)
}

// Markdown parses and  returns the converted html from a markdown []byte
// accepts two parameters
// first is the http status code
// second is the markdown string
//
// Note that: Works different than the other rest's functions.
func (r *Render) Markdown(markdownBytes []byte) string {
	buf := blackfriday.MarkdownCommon(markdownBytes)
	if r.Config.MarkdownSanitize {
		buf = bluemonday.UGCPolicy().SanitizeBytes(buf)
	}

	return string(buf)

}