package api

import (
	"bytes"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"sync"
	"testing"
	"time"

	"github.com/go-chi/chi/v5"

	"git.gophernest.net/azpect/ResumeLens/internal/handlers"
	"git.gophernest.net/azpect/ResumeLens/internal/models"
)

func makeAnalyzeRequest(t *testing.T, ip string) *http.Request {
	t.Helper()
	body := &bytes.Buffer{}
	w := multipart.NewWriter(body)

	part, err := w.CreateFormFile("resume", "resume.pdf")
	if err != nil {
		t.Fatalf("create form file: %v", err)
	}
	if _, err := part.Write([]byte("fake-pdf")); err != nil {
		t.Fatalf("write form file: %v", err)
	}
	if err := w.WriteField("job_description", "Go role"); err != nil {
		t.Fatalf("write field: %v", err)
	}
	if err := w.Close(); err != nil {
		t.Fatalf("close writer: %v", err)
	}

	req := httptest.NewRequest(http.MethodPost, "/api/analyze", body)
	req.Header.Set("Content-Type", w.FormDataContentType())
	req.RemoteAddr = ip + ":12345"
	return req
}

func TestE2E_8_2_6_RateLimitEnforcementScenario(t *testing.T) {
	resetRateLimiter()
	restore := handlers.SetAnalyzeResumeForTesting(func(_ io.Reader, _ string) (*models.AnalysisResult, error) {
		return &models.AnalysisResult{OverallScore: 80, Summary: "ok"}, nil
	})
	t.Cleanup(restore)

	r := chi.NewRouter()
	Mount(r)

	for i := 0; i < 10; i++ {
		rr := httptest.NewRecorder()
		r.ServeHTTP(rr, makeAnalyzeRequest(t, "127.0.0.1"))
		if rr.Code != http.StatusOK {
			t.Fatalf("request %d expected 200, got %d", i+1, rr.Code)
		}
	}

	blocked := httptest.NewRecorder()
	r.ServeHTTP(blocked, makeAnalyzeRequest(t, "127.0.0.1"))
	if blocked.Code != http.StatusTooManyRequests {
		t.Fatalf("expected 11th request to be 429, got %d", blocked.Code)
	}
}

func TestE2E_8_3_2_NonAIEndpointsFast(t *testing.T) {
	resetRateLimiter()
	r := chi.NewRouter()
	Mount(r)

	start := time.Now()
	req := httptest.NewRequest(http.MethodGet, "/api/unknown", nil)
	rr := httptest.NewRecorder()
	r.ServeHTTP(rr, req)
	dur := time.Since(start)

	if rr.Code != http.StatusNotFound {
		t.Fatalf("expected 404 for unknown endpoint, got %d", rr.Code)
	}
	if dur >= time.Second {
		t.Fatalf("expected non-AI endpoint under 1 second, got %v", dur)
	}
}

func TestEdge_10_4_1_MultipleSimultaneousRequestsDifferentIPs(t *testing.T) {
	resetRateLimiter()
	restore := handlers.SetAnalyzeResumeForTesting(func(_ io.Reader, _ string) (*models.AnalysisResult, error) {
		return &models.AnalysisResult{OverallScore: 80, Summary: "ok"}, nil
	})
	t.Cleanup(restore)

	r := chi.NewRouter()
	Mount(r)

	var wg sync.WaitGroup
	results := make(chan int, 50)
	for i := 0; i < 50; i++ {
		wg.Add(1)
		ip := fmt.Sprintf("10.0.0.%d", i+1)
		go func(clientIP string) {
			defer wg.Done()
			rr := httptest.NewRecorder()
			r.ServeHTTP(rr, makeAnalyzeRequest(t, clientIP))
			results <- rr.Code
		}(ip)
	}

	wg.Wait()
	close(results)

	for code := range results {
		if code != http.StatusOK {
			t.Fatalf("expected all concurrent different-IP requests to succeed, got status %d", code)
		}
	}
}

func TestEdge_10_4_2_RateLimiterThreadSafetySameIP(t *testing.T) {
	resetRateLimiter()
	restore := handlers.SetAnalyzeResumeForTesting(func(_ io.Reader, _ string) (*models.AnalysisResult, error) {
		return &models.AnalysisResult{OverallScore: 80, Summary: "ok"}, nil
	})
	t.Cleanup(restore)

	r := chi.NewRouter()
	Mount(r)

	var wg sync.WaitGroup
	results := make(chan int, 20)
	for i := 0; i < 20; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			rr := httptest.NewRecorder()
			r.ServeHTTP(rr, makeAnalyzeRequest(t, "127.0.0.1"))
			results <- rr.Code
		}()
	}

	wg.Wait()
	close(results)

	okCount := 0
	blockedCount := 0
	for code := range results {
		switch code {
		case http.StatusOK:
			okCount++
		case http.StatusTooManyRequests:
			blockedCount++
		default:
			t.Fatalf("unexpected status code: %d", code)
		}
	}

	if okCount != 10 || blockedCount != 10 {
		t.Fatalf("expected 10 success and 10 blocked, got %d success and %d blocked", okCount, blockedCount)
	}
}