package main

import (
	"fmt"
	htemplate "html/template"
	"os"
	"path"
	"strings"
	"text/template"

	"github.com/BurntSushi/toml"
)

// Config contains site configuration.
type Config struct {
	Title      string            `toml:"title"`
	URLs       []string          `toml:"urls"`
	Tasks      []*Task           `toml:"tasks"`
	Feeds      map[string]string `toml:"feeds"`
	Permalinks map[string]string `toml:"permalinks"`
	permalinks map[string]*template.Template
	templates  *Templates
}

// Task represents a site build task.
type Task struct {
	InputExt    string `toml:"input_ext"`    // input file extension
	OutputExt   string `toml:"output_ext"`   // output file extension
	TemplateExt string `toml:"template_ext"` // template file extension
	PreProcess  string `toml:"preprocess"`   // preprocess command
	PostProcess string `toml:"postprocess"`  // postprocess command
	StaticDir   string `toml:"static_dir"`   // static file directory
	OutputDir   string `toml:"output_dir"`   // output directory
	UglyURLs    bool   `toml:"ugly_urls"`    // whether to use ugly URLs
}

// LoadConfig loads the configuration from the provided path.
func LoadConfig(path string) (*Config, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	c := &Config{}
	if _, err := toml.DecodeReader(f, c); err != nil {
		return nil, err
	}

	// Parse permalinks
	c.permalinks = map[string]*template.Template{}
	for s := range c.Permalinks {
		t := template.New(fmt.Sprintf("permalink %q", s)).Funcs(funcs)
		_, err := t.Parse(c.Permalinks[s])
		if err != nil {
			return nil, err
		}
		c.permalinks[s] = t
	}

	// Site contains site metadata passed to templates
	type Site struct {
		Title string
		URLs  []string
	}

	funcs["site"] = func() Site {
		return Site{
			Title: c.Title,
			URLs:  c.URLs,
		}
	}
	funcs["partial"] = func(name string, data interface{}) (interface{}, error) {
		t, ok := c.templates.FindPartial(name)
		if !ok {
			return "", fmt.Errorf("Error: partial %q not found", name)
		}
		var b strings.Builder
		if err := t.Execute(&b, data); err != nil {
			return "", err
		}
		return b.String(), nil
	}

	// Initialize templates
	c.templates = NewTemplates()
	c.templates.Funcs(funcs)

	return c, nil
}

var funcs = map[string]interface{}{
	"safeHTML":     func(s string) htemplate.HTML { return htemplate.HTML(s) },
	"safeHTMLAttr": func(s string) htemplate.HTMLAttr { return htemplate.HTMLAttr(s) },
	"safeCSS":      func(s string) htemplate.CSS { return htemplate.CSS(s) },
	"safeJS":       func(s string) htemplate.JS { return htemplate.JS(s) },
	"safeURL":      func(s string) htemplate.URL { return htemplate.URL(s) },
	"path":         func() pathFuncs { return pathFuncs{} },
}

type pathFuncs struct{}

func (pathFuncs) Base(s string) string            { return path.Base(s) }
func (pathFuncs) Clean(s string) string           { return path.Clean(s) }
func (pathFuncs) Dir(s string) string             { return path.Dir(s) }
func (pathFuncs) Ext(s string) string             { return path.Ext(s) }
func (pathFuncs) Join(elem ...string) string      { return path.Join(elem...) }
func (pathFuncs) Split(s string) (string, string) { return path.Split(s) }