package http

import (
	"context"
	"math"
	"net"
	"net/http"
	"strings"
	"time"

	"github.com/debridmediamanager/zurg/internal/config"
	"github.com/debridmediamanager/zurg/pkg/logutil"

	cmap "github.com/orcaman/concurrent-map/v2"
)

const (
	RATE_LIMIT_FACTOR = 4 // should always be > 1
)

type HTTPClient struct {
	client       *http.Client
	maxRetries   int
	backoff      func(attempt int) time.Duration
	getRetryIncr func(resp *http.Response, hasRangeHeader bool, err error) int
	bearerToken  string
	cfg          config.ConfigInterface
	ipv6         cmap.ConcurrentMap[string, string]
	log          *logutil.Logger
}

func NewHTTPClient(token string, maxRetries int, timeoutSecs int, cfg config.ConfigInterface, log *logutil.Logger) *HTTPClient {
	client := HTTPClient{
		bearerToken: token,
		client: &http.Client{
			Timeout: time.Duration(timeoutSecs) * time.Second,
		},
		maxRetries: maxRetries * RATE_LIMIT_FACTOR,
		backoff: func(attempt int) time.Duration {
			maxDuration := 60
			backoff := int(math.Pow(2, float64(attempt)))
			if backoff > maxDuration {
				backoff = maxDuration
			}
			return time.Duration(backoff) * time.Second
		},
		getRetryIncr: func(resp *http.Response, hasRangeHeader bool, err error) int {
			if resp != nil {
				if resp.StatusCode == 429 || resp.StatusCode == 400 || resp.StatusCode == 403 {
					return 1 // retry but don't increment attempt
				}
				if resp.StatusCode != http.StatusPartialContent && hasRangeHeader {
					return 1
				}
				return 0 // don't retry
			} else if err != nil {
				errStr := err.Error()
				if strings.Contains(errStr, "EOF") || strings.Contains(errStr, "connection reset") || strings.Contains(errStr, "no such host") {
					return 1 // retry but don't increment attempt
				} else {
					return RATE_LIMIT_FACTOR
				}
			}
			return RATE_LIMIT_FACTOR // retry and increment attempt
		},
		cfg:  cfg,
		ipv6: cmap.New[string](),
		log:  log,
	}

	if cfg.ShouldForceIPv6() {
		dialer := &net.Dialer{}
		dialContext := func(ctx context.Context, network, address string) (net.Conn, error) {
			host, port, err := net.SplitHostPort(address)
			if err != nil {
				return nil, err
			}
			if ipv6Address, ok := client.ipv6.Get(address); ok {
				return dialer.DialContext(ctx, network, ipv6Address)
			}

			ips, err := net.DefaultResolver.LookupIPAddr(ctx, host)
			if err != nil {
				return nil, err
			}

			for _, ip := range ips {
				if ip.IP.To4() == nil { // IPv6 address found
					ip6Host := ip.IP.String()
					ipv6Address := net.JoinHostPort(ip6Host, port)
					client.ipv6.Set(address, ipv6Address)
					return dialer.DialContext(ctx, network, ipv6Address)
				}
			}
			return dialer.DialContext(ctx, network, address)
		}

		transport := &http.Transport{
			DialContext: dialContext,
		}
		client.client.Transport = transport
	}

	return &client
}

func (r *HTTPClient) Do(req *http.Request) (*http.Response, error) {
	if r.bearerToken != "" {
		req.Header.Set("Authorization", "Bearer "+r.bearerToken)
	}
	// check if Range header is set
	hasRangeHeader := req.Header.Get("Range") != ""

	var resp *http.Response
	var err error
	attempt := 0
	for {
		resp, err = r.client.Do(req)
		if incr := r.getRetryIncr(resp, hasRangeHeader, err); incr > 0 {
			attempt += incr
			if attempt > r.maxRetries {
				break
			}
			if incr >= RATE_LIMIT_FACTOR {
				time.Sleep(r.backoff(attempt))
			} else {
				time.Sleep(time.Duration(r.cfg.GetRateLimitSleepSeconds()) * time.Second) // extra delay
			}
			if resp != nil {
				resp.Body.Close()
			}
		} else {
			// if incr == 0, don't retry anymore
			break
		}
	}
	return resp, err
}