package api

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"sync"
	"time"

	"github.com/frenocorp/pop/internal/config"
	"github.com/frenocorp/pop/internal/auth"
)

type ProtonMailClient struct {
	baseURL      string
	httpClient   *http.Client
	config       *config.Config
	rateLimiter  *RateLimiter
	authHeader   string
	authMu       sync.RWMutex
	sessionRefresher auth.SessionRefresher
}

type RateLimiter struct {
	mu          sync.Mutex
	requests    []time.Time
	limit       int
	window      time.Duration
}

func NewProtonMailClient(cfg *config.Config, refresher auth.SessionRefresher) *ProtonMailClient {
	return &ProtonMailClient{
		baseURL:    cfg.APIBaseURL,
		httpClient: &http.Client{Timeout: time.Duration(cfg.TimeoutSec) * time.Second},
		config:     cfg,
		sessionRefresher: refresher,
		rateLimiter: &RateLimiter{
			requests: make([]time.Time, 0, cfg.RateLimitReq),
			limit:    cfg.RateLimitReq,
			window:   time.Duration(cfg.RateLimitWin) * time.Second,
		},
	}
}

func (c *ProtonMailClient) SetAuthHeader(token string) {
	c.authMu.Lock()
	defer c.authMu.Unlock()
	c.authHeader = token
}

func (c *ProtonMailClient) getAuthHeader() string {
	c.authMu.RLock()
	defer c.authMu.RUnlock()
	return c.authHeader
}

func (c *ProtonMailClient) refreshAuth() error {
	if c.sessionRefresher == nil {
		return fmt.Errorf("no session refresher configured")
	}
	return c.sessionRefresher.RefreshToken()
}

func (c *ProtonMailClient) GetBaseURL() string {
	return c.baseURL
}

func (rl *RateLimiter) Wait() {
	rl.mu.Lock()
	defer rl.mu.Unlock()

	now := time.Now()
	windowStart := now.Add(-rl.window)

	// Remove old requests outside the window
	validRequests := make([]time.Time, 0, rl.limit)
	for _, t := range rl.requests {
		if t.After(windowStart) {
			validRequests = append(validRequests, t)
		}
	}
	rl.requests = validRequests

	// Wait if at limit
	if len(rl.requests) >= rl.limit {
		sleep := rl.requests[0].Add(rl.window).Sub(now)
		if sleep > 0 {
			time.Sleep(sleep)
		}
	}
}

func (c *ProtonMailClient) Do(req *http.Request) (*http.Response, error) {
	return c.DoWithContext(context.Background(), req)
}

func (c *ProtonMailClient) DoWithContext(ctx context.Context, req *http.Request) (*http.Response, error) {
	c.rateLimiter.Wait()

	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.getAuthHeader()))
	req.Header.Set("Accept", "application/json")

	// Check if request has its own context
	if ctx != context.Background() {
		req = req.WithContext(ctx)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, err
	}

	// Record the request
	c.rateLimiter.mu.Lock()
	c.rateLimiter.requests = append(c.rateLimiter.requests, time.Now())
	c.rateLimiter.mu.Unlock()

	// Check for 401 and attempt refresh
	if resp.StatusCode == http.StatusUnauthorized {
		// Close the current response body
		resp.Body.Close()

		// Attempt to refresh the token
		if err := c.refreshAuth(); err != nil {
			return resp, fmt.Errorf("401 received and refresh failed: %w", err)
		}

		// Retry the request with new token
		// Clone the request to reset any body position
		retryReq := req.Clone(ctx)
		retryReq.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.getAuthHeader()))

		resp, err = c.httpClient.Do(retryReq)
		if err != nil {
			return nil, err
		}

		// Record the retry request
		c.rateLimiter.mu.Lock()
		c.rateLimiter.requests = append(c.rateLimiter.requests, time.Now())
		c.rateLimiter.mu.Unlock()
	}

	// Check for other API errors
	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(resp.Body)
		var apiErr APIError
		if err := json.Unmarshal(body, &apiErr); err == nil {
			resp.Body = io.NopCloser(io.MultiReader(io.NopCloser(bytes.NewReader(body)), bytes.NewReader(body)))
			return resp, &apiErr
		}
	}

	return resp, nil
}

type APIError struct {
	HTTPStatus int    `json:"-"`
	Code       int    `json:"Code,omitempty"`
	Message    string `json:"Message,omitempty"`
}

func (e *APIError) Error() string {
	return fmt.Sprintf("API error %d: %s", e.HTTPStatus, e.Message)
}

// Helper function to create a request with context
func NewRequestWithContext(ctx context.Context, method, url string, body io.Reader) (*http.Request, error) {
	req, err := http.NewRequestWithContext(ctx, method, url, body)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")
	return req, nil
}