package main

import (
	"fmt"
	"os"
	"strings"
	"text/template"

	"github.com/pelletier/go-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 {
	Input       []string          `toml:"input"`       // input file suffixes
	OutputExt   string            `toml:"output"`      // output file suffix
	TemplateExt string            `toml:"template"`    // template file suffix
	Preprocess  map[string]string `toml:"preprocess"`  // preprocess commands
	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
}

func (t *Task) Match(ext string) bool {
	for i := range t.Input {
		if t.Input[i] == ext {
			return true
		}
	}
	return false
}

// 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.NewDecoder(f).Decode(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
}