package config

import (
	"flag"
	"fmt"
	"os"
	"path/filepath"

	"gopkg.in/yaml.v3"
)

type Config struct {
	ContentDir string
	Listen     string
	Title      string
	Author     string
	BaseURL    string
}

type bookYAML struct {
	Title  string `yaml:"title"`
	Author string `yaml:"author"`
}

func Load() (*Config, error) {
	c := &Config{}
	flag.StringVar(&c.ContentDir, "content", ".", "path to markdown content directory")
	flag.StringVar(&c.Listen, "listen", ":8080", "listen address")
	flag.StringVar(&c.Title, "title", "", "site title (overrides book.yaml)")
	flag.StringVar(&c.BaseURL, "base-url", "", "base URL prefix (e.g. /docs)")
	flag.Parse()

	abs, err := filepath.Abs(c.ContentDir)
	if err != nil {
		return nil, fmt.Errorf("content dir: %w", err)
	}
	c.ContentDir = abs

	info, err := os.Stat(c.ContentDir)
	if err != nil || !info.IsDir() {
		return nil, fmt.Errorf("content dir %q is not a directory", c.ContentDir)
	}

	c.loadBookYAML()
	return c, nil
}

func (c *Config) loadBookYAML() {
	data, err := os.ReadFile(filepath.Join(c.ContentDir, "book.yaml"))
	if err != nil {
		return
	}
	var b bookYAML
	if err := yaml.Unmarshal(data, &b); err != nil {
		return
	}
	if c.Title == "" && b.Title != "" {
		c.Title = b.Title
	}
	if c.Author == "" && b.Author != "" {
		c.Author = b.Author
	}
}