package cyutils

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"sync"

	"golang.org/x/time/rate"
)

func WithWorkers[T any](workers int, arr []T, fn func(worker int, item T)) {
	workersChan := make(chan struct{}, workers)
	ingestChan := make(chan T, len(arr))

	for _, item := range arr {
		ingestChan <- item
	}
	close(ingestChan)

	wg := sync.WaitGroup{}
	for i := 0; i < workers; i++ {
		workersChan <- struct{}{}
		wg.Add(1)
		go func(worker int) {
			defer wg.Done()
			defer func() { <-workersChan }()
			for {
				item, ok := <-ingestChan
				// We're done processing totally
				if !ok {
					return
				}
				fn(worker, item)
			}
		}(i)
	}
	wg.Wait()
}
func Batched[T any](arr []T, batchSize int, fn func(batch []T)) {
	for i := 0; i < len(arr); i += batchSize {
		start := i
		end := min(i+batchSize, len(arr))
		batch := arr[start:end]
		fn(batch)
	}
}

type RateLimitedTransport struct {
	base    http.RoundTripper // Underlying transport
	limiter *rate.Limiter     // Rate limiter
}

// RoundTrip enforces rate limiting before executing the request
func (t *RateLimitedTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	ctx := req.Context()
	if err := t.limiter.Wait(ctx); err != nil {
		return nil, err // Handle context cancellation/timeout
	}
	return t.base.RoundTrip(req)
}
func LimitedHttp(rps float64, burst int) *http.Client {
	baseTransport := &http.Transport{
		MaxIdleConns:        100,
		MaxIdleConnsPerHost: 10,
	}

	// Initialize rate limiter
	limiter := rate.NewLimiter(rate.Limit(rps), burst)

	// Wrap transport with rate limiting
	transport := &RateLimitedTransport{
		base:    baseTransport,
		limiter: limiter,
	}

	// Return configured client
	return &http.Client{
		Transport: transport,
	}
}

func RequestCached[T any](req *http.Request, filename string) (T, error) {
	var zero T

	data, err := os.ReadFile(filename)
	if err != nil {
		if !os.IsNotExist(err) {
			return zero, fmt.Errorf("failed to read cache: %w", err)
		}

		resp, httpErr := http.DefaultClient.Do(req)
		if httpErr != nil {
			return zero, fmt.Errorf("HTTP request failed: %w", httpErr)
		}
		defer resp.Body.Close()

		body, readErr := io.ReadAll(resp.Body)
		if readErr != nil {
			return zero, fmt.Errorf("failed to read response body: %w", readErr)
		}

		dir := filepath.Dir(filename)
		if dir != "." && dir != "" {
			if mkErr := os.MkdirAll(dir, 0o755); mkErr != nil {
				return zero, fmt.Errorf("failed to create cache dir %s: %w", dir, mkErr)
			}
		}
		if writeErr := os.WriteFile(filename, body, 0o644); writeErr != nil {
			return zero, fmt.Errorf("failed to write cache %s: %w", filename, writeErr)
		}
		data = body
	}

	if _, ok := any(zero).([]byte); ok {
		return any(data).(T), nil
	}

	var out T
	if err := json.Unmarshal(data, &out); err != nil {
		return zero, fmt.Errorf("failed to unmarshal cached response: %w", err)
	}
	return out, nil
}

func RequestCachedBytes(req *http.Request, filename string) ([]byte, error) {
	return RequestCached[[]byte](req, filename)
}