package chat

import (
	"context"
	"sync"
	"time"

	"cursor-api-proxy/internal/svc"
	apitypes "cursor-api-proxy/internal/types"
	"cursor-api-proxy/pkg/domain/types"

	"github.com/zeromicro/go-zero/core/logx"
)

const modelCacheTTLMs = 5 * 60 * 1000

type ModelCache struct {
	At     int64
	Models []types.CursorCliModel
}

type ModelCacheRef struct {
	mu       sync.Mutex
	cache    *ModelCache
	inflight bool
	waiters  []chan struct{}
}

var globalModelCache = &ModelCacheRef{}

type ModelsLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewModelsLogic(ctx context.Context, svcCtx *svc.ServiceContext) *ModelsLogic {
	return &ModelsLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *ModelsLogic) Models() (resp *apitypes.ModelsResponse, err error) {
	now := time.Now().UnixMilli()

	globalModelCache.mu.Lock()
	if globalModelCache.cache != nil && now-globalModelCache.cache.At <= modelCacheTTLMs {
		cache := globalModelCache.cache
		globalModelCache.mu.Unlock()
		return buildModelsResponse(cache.Models), nil
	}

	if globalModelCache.inflight {
		ch := make(chan struct{}, 1)
		globalModelCache.waiters = append(globalModelCache.waiters, ch)
		globalModelCache.mu.Unlock()
		<-ch
		globalModelCache.mu.Lock()
		cache := globalModelCache.cache
		globalModelCache.mu.Unlock()
		return buildModelsResponse(cache.Models), nil
	}

	globalModelCache.inflight = true
	globalModelCache.mu.Unlock()

	fetched, err := types.ListCursorCliModels(l.svcCtx.Config.AgentBin, l.svcCtx.Config.TimeoutMs)

	globalModelCache.mu.Lock()
	globalModelCache.inflight = false
	if err == nil {
		globalModelCache.cache = &ModelCache{At: time.Now().UnixMilli(), Models: fetched}
	}
	waiters := globalModelCache.waiters
	globalModelCache.waiters = nil
	globalModelCache.mu.Unlock()

	for _, ch := range waiters {
		ch <- struct{}{}
	}

	if err != nil {
		return nil, err
	}

	return buildModelsResponse(fetched), nil
}

func buildModelsResponse(mods []types.CursorCliModel) *apitypes.ModelsResponse {
	models := make([]apitypes.ModelData, len(mods))
	for i, m := range mods {
		models[i] = apitypes.ModelData{
			Id:      m.ID,
			Object:  "model",
			OwnedBy: "cursor",
		}
	}

	ids := make([]string, len(mods))
	for i, m := range mods {
		ids[i] = m.ID
	}
	aliases := types.GetAnthropicModelAliases(ids)
	for _, a := range aliases {
		models = append(models, apitypes.ModelData{
			Id:      a.ID,
			Object:  "model",
			OwnedBy: "cursor",
		})
	}

	return &apitypes.ModelsResponse{
		Object: "list",
		Data:   models,
	}
}