package providers

import (
	"fmt"
	"log/slog"
	"sync"
	"time"

	"github.com/chenxin/hunjing/mcp/web-search/internal/config"
	"github.com/chenxin/hunjing/mcp/web-search/internal/models"
)

// Registry 管理多 provider 注册和查询。
type Registry struct {
	mu        sync.RWMutex
	providers map[models.ProviderKind]SearchProvider
}

func NewRegistry() *Registry {
	return &Registry{
		providers: make(map[models.ProviderKind]SearchProvider),
	}
}

// Register 注册 provider。
func (r *Registry) Register(p SearchProvider) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.providers[p.Name()] = p
}

// Get 按名称获取 provider。
func (r *Registry) Get(name models.ProviderKind) (SearchProvider, bool) {
	r.mu.RLock()
	defer r.mu.RUnlock()
	p, ok := r.providers[name]
	return p, ok
}

// All 返回所有已注册 provider。
func (r *Registry) All() []SearchProvider {
	r.mu.RLock()
	defer r.mu.RUnlock()
	out := make([]SearchProvider, 0, len(r.providers))
	for _, p := range r.providers {
		out = append(out, p)
	}
	return out
}

// Names 返回所有已注册的 provider 名称。
func (r *Registry) Names() []models.ProviderKind {
	r.mu.RLock()
	defer r.mu.RUnlock()
	out := make([]models.ProviderKind, 0, len(r.providers))
	for name := range r.providers {
		out = append(out, name)
	}
	return out
}

// SetupFromConfig 根据配置创建并注册所有启用的 provider。
func SetupFromConfig(cfg *config.Config) (*Registry, error) {
	reg := NewRegistry()

	if cfg.Providers.Tavily.Enabled {
		if len(cfg.Providers.Tavily.APIKeys) == 0 {
			slog.Warn("tavily: enabled but no API keys configured, skipping")
		} else {
			reg.Register(NewTavilyProvider(cfg.Providers.Tavily.Timeout, cfg.Providers.Tavily.MaxResults))
		}
	}
	if cfg.Providers.Brave.Enabled {
		if len(cfg.Providers.Brave.APIKeys) == 0 {
			slog.Warn("brave: enabled but no API keys configured, skipping")
		} else {
			reg.Register(NewBraveProvider(cfg.Providers.Brave.Timeout, cfg.Providers.Brave.MaxResults))
		}
	}

	if len(reg.Names()) == 0 {
		return nil, fmt.Errorf("no providers enabled or configured")
	}
	return reg, nil
}

// SetupFromConfigWithOverrides 从配置创建注册中心，并允许使用显式 provider 配置覆盖配置文件。
// 本函数方便测试和动态配置场景。
func SetupFromConfigWithOverrides(
	cfg *config.Config,
	overrideTimeout time.Duration,
	overrideMaxResults int,
) (*Registry, error) {
	reg := NewRegistry()

	if cfg.Providers.Tavily.Enabled && len(cfg.Providers.Tavily.APIKeys) > 0 {
		t := cfg.Providers.Tavily.Timeout
		m := cfg.Providers.Tavily.MaxResults
		if overrideTimeout > 0 {
			t = overrideTimeout
		}
		if overrideMaxResults > 0 {
			m = overrideMaxResults
		}
		reg.Register(NewTavilyProvider(t, m))
	}
	if cfg.Providers.Brave.Enabled && len(cfg.Providers.Brave.APIKeys) > 0 {
		t := cfg.Providers.Brave.Timeout
		m := cfg.Providers.Brave.MaxResults
		if overrideTimeout > 0 {
			t = overrideTimeout
		}
		if overrideMaxResults > 0 {
			m = overrideMaxResults
		}
		reg.Register(NewBraveProvider(t, m))
	}

	if len(reg.Names()) == 0 {
		return nil, fmt.Errorf("no providers enabled or configured")
	}
	return reg, nil
}