package main

import (
	"bytes"
	"log"
	"os"
	"os/exec"
	"path"
	"strings"
	"text/template"

	"github.com/BurntSushi/toml"
)

// Config contains site configuration.
type Config struct {
	Title     string            `toml:"title"` // site title
	URLs      []string          `toml:"urls"`  // site URLs
	Feeds     map[string]string `toml:"feeds"` // site feeds
	Tasks     map[string]*Task  `toml:"tasks"` // site tasks
	Templates *Templates        `toml:"-"`     // site 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
	PostProcess string `toml:"postprocess"`  // postprocess command
	StaticDir   string `toml:"static_dir"`   // static file directory
	OutputDir   string `toml:"output_dir"`   // output directory
}

func (t Task) Format(p *Page) (string, []byte) {
	path := path.Join(p.Path, "index"+t.OutputExt)

	// Run a custom command.
	if t.PostProcess != "" {
		split := strings.Split(t.PostProcess, " ")
		cmd := exec.Command(split[0], split[1:]...)
		buf := new(bytes.Buffer)
		cmd.Stdin = strings.NewReader(p.Content)
		cmd.Stdout = buf
		if err := cmd.Run(); err != nil {
			log.Fatal(err)
		}
		return path, buf.Bytes()
	}

	return path, []byte(p.Content)
}

// DefaultConfig returns the default configuration.
func DefaultConfig() *Config {
	c := new(Config)
	c.Feeds = make(map[string]string)
	c.Tasks = make(map[string]*Task)
	c.Tasks["gemini"] = &Task{
		InputExt:    ".gmi",
		OutputExt:   ".gmi",
		TemplateExt: ".gmi",
		StaticDir:   "static",
		OutputDir:   "public",
	}
	return c
}

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

	return c, nil
}

// LoadTemplates loads templates from the provided path.
func (c *Config) LoadTemplates(path string) error {
	// Site contains site metadata passed to templates
	type Site struct {
		Title string
		URLs  []string
	}

	// Load templates
	c.Templates = NewTemplates()
	c.Templates.Funcs(template.FuncMap{
		"site": func() Site {
			return Site{
				Title: c.Title,
				URLs:  c.URLs,
			}
		},
	})
	c.Templates.LoadDefault()
	return c.Templates.Load(path)
}