package settings

import (
	"context"
	"strings"

	"apps/backend/internal/module/ai"
	"apps/backend/internal/module/member/domain"
	"apps/backend/internal/svc"
	"apps/backend/internal/types"
)

func resolveAPIKey(svcCtx *svc.ServiceContext, st *domain.UserSettings, provider string) (key string, platformAvailable bool) {
	provider = ai.NormalizeProvider(provider)
	// 1) user BYOK for this provider
	if st != nil {
		if k := st.KeyForProvider(provider); k != "" {
			return k, platformKeyAvailable(svcCtx, provider)
		}
	}
	// 2) platform key
	return platformKey(svcCtx, provider), platformKeyAvailable(svcCtx, provider)
}

func platformKey(svcCtx *svc.ServiceContext, provider string) string {
	if svcCtx == nil {
		return ""
	}
	switch ai.NormalizeProvider(provider) {
	case ai.ProviderOpenCodeGo:
		return strings.TrimSpace(svcCtx.Config.Platform.OpenCodeKey)
	default:
		k := strings.TrimSpace(svcCtx.Config.Platform.XAIKey)
		if k == "" {
			k = strings.TrimSpace(svcCtx.Config.Platform.AIKey)
		}
		return k
	}
}

func platformKeyAvailable(svcCtx *svc.ServiceContext, provider string) bool {
	return platformKey(svcCtx, provider) != ""
}

// loadModelsForProvider — 真拉 + 5 分鐘快取；失敗用 fallback（不回空 list）
func loadModelsForProvider(ctx context.Context, svcCtx *svc.ServiceContext, st *domain.UserSettings, provider string) (list []string, fromCache bool, modelsErr string) {
	provider = ai.NormalizeProvider(provider)
	key, _ := resolveAPIKey(svcCtx, st, provider)
	if key == "" {
		return ai.FallbackModels(provider), false, "尚未設定 API key（會員 BYOK 或平台 key）"
	}
	if svcCtx.AIRegistry == nil {
		return ai.FallbackModels(provider), false, "AI registry not configured"
	}
	list, fromCache, err := svcCtx.AIRegistry.ListModelsCached(ctx, provider, key)
	if err != nil {
		return ai.FallbackModels(provider), false, err.Error()
	}
	return list, fromCache, ""
}

// pickModel：優先用會員已存模型；即使暫時不在列表也保留（不寫死改成別台）
func pickModel(preferred string, list []string) string {
	preferred = strings.TrimSpace(preferred)
	if preferred != "" {
		return preferred
	}
	if len(list) > 0 {
		return list[0]
	}
	return ""
}

func buildAiSettingsData(ctx context.Context, svcCtx *svc.ServiceContext, st *domain.UserSettings, modelsProvider string) *types.AiSettingsData {
	if st == nil {
		st = domain.DefaultSettings(0)
	}
	savedProvider := ai.NormalizeProvider(st.Provider)
	if savedProvider == "" {
		savedProvider = ai.ProviderXAI
	}
	modelsProvider = ai.NormalizeProvider(modelsProvider)
	if modelsProvider == "" {
		modelsProvider = savedProvider
	}

	list, fromCache, modelsErr := loadModelsForProvider(ctx, svcCtx, st, modelsProvider)
	// 顯示／回傳都以會員存檔為準
	selected := pickModel(st.Model, list)
	savedModel := strings.TrimSpace(st.Model)
	if modelsProvider == savedProvider && selected != "" {
		savedModel = selected
	}

	keyConfigured := st.HasKeyForProvider(savedProvider)
	platformAvail := platformKeyAvailable(svcCtx, savedProvider)

	return &types.AiSettingsData{
		Provider:                 savedProvider,
		Model:                    savedModel,
		ResearchProvider:         savedProvider,
		ResearchModel:            savedModel,
		ApiKeyConfigured:         keyConfigured,
		ResearchApiKeyConfigured: keyConfigured || st.ResearchAPIKeyConfigured,
		PlatformKeyAvailable:     platformAvail,
		Models:                   list,
		ModelsProvider:           modelsProvider,
		SelectedModel:            selected,
		ModelsFromCache:          fromCache,
		ModelsError:              modelsErr,
	}
}