// Package config loads yaju-keisatsu's YAML configuration file.
package config

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

	"gopkg.in/yaml.v3"
)

type Config struct {
	ListenAddr    string  `yaml:"listen_addr"`
	WebhookSecret string  `yaml:"webhook_secret"`
	Forgejo       Forgejo `yaml:"forgejo"`
	Bot           Bot     `yaml:"bot"`
	// PhrasesFile, if set, is loaded and merged with Phrases. It lets a
	// deployment point at the repo's community-maintained phrases.yaml while
	// still keeping any private additions inline below.
	PhrasesFile string   `yaml:"phrases_file"`
	Phrases     []string `yaml:"phrases"`
}

type phrasesFile struct {
	Phrases []string `yaml:"phrases"`
}

type Forgejo struct {
	BaseURL string `yaml:"base_url"`
	Token   string `yaml:"token"`
}

type Bot struct {
	// Username is the Forgejo account the API token belongs to. Comments
	// authored by this account are ignored so the bot never replies to itself.
	Username string `yaml:"username"`
	// BranchPrefix is prepended to the auto-generated correction branch name.
	BranchPrefix string `yaml:"branch_prefix"`
	// TargetExtensions limits which pushed files are scanned for corrections.
	// An empty list scans every file.
	TargetExtensions []string `yaml:"target_extensions"`
}

func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}

	cfg := &Config{
		ListenAddr: ":8080",
		Bot: Bot{
			BranchPrefix: "bot/goroku-fix/",
		},
	}
	if err := yaml.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}

	if cfg.PhrasesFile != "" {
		fp := cfg.PhrasesFile
		if !filepath.IsAbs(fp) {
			fp = filepath.Join(filepath.Dir(path), fp)
		}
		data, err := os.ReadFile(fp)
		if err != nil {
			return nil, fmt.Errorf("read phrases_file: %w", err)
		}
		var pf phrasesFile
		if err := yaml.Unmarshal(data, &pf); err != nil {
			return nil, fmt.Errorf("parse phrases_file: %w", err)
		}
		cfg.Phrases = append(pf.Phrases, cfg.Phrases...)
	}

	if cfg.Forgejo.BaseURL == "" {
		return nil, fmt.Errorf("forgejo.base_url is required")
	}
	if cfg.Forgejo.Token == "" {
		return nil, fmt.Errorf("forgejo.token is required")
	}
	if cfg.WebhookSecret == "" {
		return nil, fmt.Errorf("webhook_secret is required")
	}
	if len(cfg.Phrases) == 0 {
		return nil, fmt.Errorf("phrases list is empty (set phrases and/or phrases_file)")
	}

	return cfg, nil
}