// Package config holds all global configuration parameters for sese-engine.
// config 包存放 sese-engine 的所有全局配置参数。
package config

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

	"gopkg.in/yaml.v3"
)

// Config 是完整的配置结构体
type Config struct {
	Index      IndexConfig      `yaml:"index"`
	Crawler    CrawlerConfig    `yaml:"crawler"`
	Search     SearchConfig     `yaml:"search"`
	Backlink   BacklinkConfig   `yaml:"backlink"`
	Storage    StorageConfig    `yaml:"storage"`
	Prometheus PrometheusConfig `yaml:"prometheus"`
}

// IndexConfig 索引/存储相关限制
type IndexConfig struct {
	MaxURLsPerKey       int `yaml:"max_urls_per_key"`
	MaxSameDomainPerKey int `yaml:"max_same_domain_per_key"`
	BigCleanThreshold   int `yaml:"big_clean_threshold"`
	MaxNewURLsPerKey    int `yaml:"max_new_urls_per_key"`
	MinURLsForNewKey    int `yaml:"min_urls_for_new_key"`
}

// CrawlerConfig 爬虫行为相关配置
type CrawlerConfig struct {
	SpiderName           string  `yaml:"spider_name"`
	Cooldown             int     `yaml:"cooldown"`
	Workers              int     `yaml:"workers"`
	CrawlFocus           float64 `yaml:"crawl_focus"`
	MaxKeywordsPerPage   int     `yaml:"max_keywords_per_page"`
	MaxEpoch             int     `yaml:"max_epoch"`
	ExpectedProsperRatio float64 `yaml:"expected_prosper_ratio"`
	EntryURL             string  `yaml:"entry_url"`
}

// SearchConfig 搜索结果排序权重配置
type SearchConfig struct {
	UseOnlineSnippet     bool    `yaml:"use_online_snippet"`
	OnlineSnippetTimeout int     `yaml:"online_snippet_timeout"`
	WeightDailyDecay     float64 `yaml:"weight_daily_decay"`
	LanguageWeight       float64 `yaml:"language_weight"`
	ConsecutiveKeyWeight float64 `yaml:"consecutive_key_weight"`
	BacklinkWeight       float64 `yaml:"backlink_weight"`
	ServerPort           int     `yaml:"server_port"`
	FlushIntervalSeconds int     `yaml:"flush_interval_seconds"`
}

// BacklinkConfig 反向链接计算相关配置
type BacklinkConfig struct {
	Baseline int `yaml:"baseline"`
}

// StorageConfig 存储配置
type StorageConfig struct {
	Path string `yaml:"path"`
}

// PrometheusConfig Prometheus监控端口配置
type PrometheusConfig struct {
	CrawlerPort  int `yaml:"crawler_port"`
	BacklinkPort int `yaml:"backlink_port"`
	SearchPort   int `yaml:"search_port"`
}

// Global 全局配置实例，加载后可通过此变量访问
var Global Config

// Load 从指定路径加载配置文件
func Load(configPath string) error {
	data, err := os.ReadFile(configPath)
	if err != nil {
		return fmt.Errorf("failed to read config file: %v", err)
	}

	var cfg Config
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return fmt.Errorf("failed to parse config file: %v", err)
	}

	Global = cfg
	return nil
}

// LoadFromSavedata 从 savedata 目录加载 config.yml
func LoadFromSavedata() error {
	configPath := filepath.Join("savedata", "config.yml")
	return Load(configPath)
}

// GetDefaultConfig 返回默认配置
func GetDefaultConfig() Config {
	return Config{
		Index: IndexConfig{
			MaxURLsPerKey:       11000,
			MaxSameDomainPerKey: 20,
			BigCleanThreshold:   10000000,
			MaxNewURLsPerKey:    10000,
			MinURLsForNewKey:    3,
		},
		Crawler: CrawlerConfig{
			SpiderName:           "loli_spider",
			Cooldown:             3,
			Workers:              22,
			CrawlFocus:           0.7,
			MaxKeywordsPerPage:   250,
			MaxEpoch:             100,
			ExpectedProsperRatio: 0.6,
			EntryURL:             "https://zh.wikipedia.org/",
		},
		Search: SearchConfig{
			UseOnlineSnippet:     true,
			OnlineSnippetTimeout: 3,
			WeightDailyDecay:     0.996,
			LanguageWeight:       0.5,
			ConsecutiveKeyWeight: 1.3,
			BacklinkWeight:       1.0,
			ServerPort:           8082,
			FlushIntervalSeconds: 60,
		},
		Backlink: BacklinkConfig{
			Baseline: 200000,
		},
		Storage: StorageConfig{
			Path: "./savedata",
		},
		Prometheus: PrometheusConfig{
			CrawlerPort:  14950,
			BacklinkPort: 14952,
			SearchPort:   14953,
		},
	}
}

// 以下是向后兼容的常量定义，使用 Global 变量的值
// 在 Init() 被调用后，这些函数会返回加载的配置值

func init() {
	// 初始化时设置默认值
	Global = GetDefaultConfig()
}

// MaxURLsPerKey 返回配置值
func MaxURLsPerKey() int { return Global.Index.MaxURLsPerKey }

// MaxSameDomainPerKey 返回配置值
func MaxSameDomainPerKey() int { return Global.Index.MaxSameDomainPerKey }

// BigCleanThreshold 返回配置值
func BigCleanThreshold() int { return Global.Index.BigCleanThreshold }

// MaxNewURLsPerKey 返回配置值
func MaxNewURLsPerKey() int { return Global.Index.MaxNewURLsPerKey }

// MinURLsForNewKey 返回配置值
func MinURLsForNewKey() int { return Global.Index.MinURLsForNewKey }

// SpiderName 返回配置值
func SpiderName() string { return Global.Crawler.SpiderName }

// CrawlerCooldown 返回配置值
func CrawlerCooldown() int { return Global.Crawler.Cooldown }

// CrawlerWorkers 返回配置值
func CrawlerWorkers() int { return Global.Crawler.Workers }

// CrawlFocus 返回配置值
func CrawlFocus() float64 { return Global.Crawler.CrawlFocus }

// MaxKeywordsPerPage 返回配置值
func MaxKeywordsPerPage() int { return Global.Crawler.MaxKeywordsPerPage }

// MaxEpoch 返回配置值
func MaxEpoch() int { return Global.Crawler.MaxEpoch }

// ExpectedProsperRatio 返回配置值
func ExpectedProsperRatio() float64 { return Global.Crawler.ExpectedProsperRatio }

// EntryURL 返回配置值
func EntryURL() string { return Global.Crawler.EntryURL }

// UseOnlineSnippet 返回配置值
func UseOnlineSnippet() bool { return Global.Search.UseOnlineSnippet }

// OnlineSnippetTimeout 返回配置值
func OnlineSnippetTimeout() int { return Global.Search.OnlineSnippetTimeout }

// WeightDailyDecay 返回配置值
func WeightDailyDecay() float64 { return Global.Search.WeightDailyDecay }

// LanguageWeight 返回配置值
func LanguageWeight() float64 { return Global.Search.LanguageWeight }

// ConsecutiveKeyWeight 返回配置值
func ConsecutiveKeyWeight() float64 { return Global.Search.ConsecutiveKeyWeight }

// BacklinkWeight 返回配置值
func BacklinkWeight() float64 { return Global.Search.BacklinkWeight }

// SearchServerPort 返回配置值
func SearchServerPort() int { return Global.Search.ServerPort }

// FlushIntervalSeconds 返回配置值
func FlushIntervalSeconds() int { return Global.Search.FlushIntervalSeconds }

// BacklinkBaseline 返回配置值
func BacklinkBaseline() int { return Global.Backlink.Baseline }

// PromPortCrawler 返回配置值
func PromPortCrawler() int { return Global.Prometheus.CrawlerPort }

// PromPortBacklink 返回配置值
func PromPortBacklink() int { return Global.Prometheus.BacklinkPort }

// PromPortSearch 返回配置值
func PromPortSearch() int { return Global.Prometheus.SearchPort }

// 为了向后兼容，保留 StoragePath 常量
const StoragePath = "./savedata"