package page

import (
	"bufio"
	"bytes"
	"io"
	"os"
	"text/template"
	"time"

	"gopkg.in/russross/blackfriday.v2"
	"gopkg.in/yaml.v2"
)

type Page struct {
	Name      string
	Head      string
	Body      string
	Date      *time.Time
	Published bool
	Templates map[string]string
}

// Can be adjusted to change the base template used in rendering
var BaseTemplate = "inc/base.html"

// Used to split the .md files into yaml and markdown
var DocumentSplit = "|---\n"

// Renders a page
func (p *Page) Render(wr io.Writer) error {
	if err := p.Read(); err != nil {
		return err
	}

	t, err := template.ParseFiles(BaseTemplate)
	if err != nil {
		return err
	}

	// Automatically pull from the yml file if applicable
	if p.Head != "" {
		t, err = t.Parse(`
			{{define "head"}}
			{{.Head}}
			{{end}}
		`)
		if err != nil {
			return err
		}
	}

	return t.Execute(wr, p)
}

// Reads in the special markdown file format for the website off of the disk
func (p *Page) Read() error {
	yamlBuf := bytes.NewBuffer(nil)
	markdownBuf := bytes.NewBuffer(nil)

	fh, err := os.Open(p.Name + ".md")
	if err != nil {
		return err
	}
	defer fh.Close()
	rdr := bufio.NewReader(fh)

	// Read in the file and split between markdown and yaml buffers
	yamlDone := false
	for {

		bytes, err := rdr.ReadBytes('\n')
		if err == io.EOF {
			break
		} else if err != nil {
			return err
		}

		// Is this the line where we stop reading the yaml and start reading markdown?
		if DocumentSplit == string(bytes) && !yamlDone {
			yamlDone = true
			continue
		}

		if !yamlDone {
			yamlBuf.Write(bytes)
		} else {
			markdownBuf.Write(bytes)
		}
	}

	err = yaml.Unmarshal(yamlBuf.Bytes(), p)
	if err != nil {
		return err
	}

	p.Body = string(blackfriday.Run(markdownBuf.Bytes()))
	return nil
}