package chinamobile_seedance

import (
	"fmt"
	"strings"
	"sync"
	"time"

	maas "maas_seedance_sdk_1.0.0_go"
)

const (
	defaultBaseURL       = "https://zhenze-huhehaote.cmecloud.cn/api/v3"
	defaultModel         = "doubao-seedance-2.0"
	defaultSubmitTimeout = 180 * time.Second
	defaultQueryTimeout  = 60 * time.Second
	sdkAcquireTimeout    = 2 * time.Second
)

var sdkSemaphore = make(chan struct{}, 4)

type seedanceSDK interface {
	CreateVideoGenerationTask(data map[string]interface{}) (string, error)
	QueryVideoGenerationTask(taskID string) (map[string]interface{}, error)
}

type seedanceSDKFactory func(baseURL, apiKey, model string) (seedanceSDK, error)

func newRealSDK(baseURL, apiKey, model string) (seedanceSDK, error) {
	baseURL = strings.TrimRight(strings.TrimSpace(baseURL), "/")
	if baseURL == "" {
		baseURL = defaultBaseURL
	}
	model = strings.TrimSpace(model)
	if model == "" {
		model = defaultModel
	}
	return runSDKCall[seedanceSDK](defaultQueryTimeout, func() (seedanceSDK, error) {
		return maas.NewMaasSeedanceClient(baseURL, apiKey, model, false)
	})
}

func runSDKCall[T any](timeout time.Duration, fn func() (T, error)) (T, error) {
	var zero T
	select {
	case sdkSemaphore <- struct{}{}:
	case <-time.After(sdkAcquireTimeout):
		return zero, fmt.Errorf("upstream_busy: sdk concurrency limit reached")
	}

	type result struct {
		value T
		err   error
	}
	var releaseOnce sync.Once
	release := func() {
		releaseOnce.Do(func() {
			<-sdkSemaphore
		})
	}
	done := make(chan result, 1)
	go func() {
		res := result{}
		defer func() {
			if r := recover(); r != nil {
				res.err = fmt.Errorf("upstream_sdk_panic: %v", r)
			}
			release()
			done <- res
		}()
		res.value, res.err = fn()
	}()

	select {
	case res := <-done:
		return res.value, res.err
	case <-time.After(timeout):
		release()
		return zero, fmt.Errorf("upstream_timeout: sdk call exceeded %s", timeout)
	}
}