package infra

import (
	"bytes"
	"io"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

// buildMultipart construye un multipart body con los archivos dados (field, filename, contenido).
func buildMultipart(t *testing.T, files []struct{ field, filename, content string }) (string, *bytes.Buffer) {
	t.Helper()
	var body bytes.Buffer
	w := multipart.NewWriter(&body)
	for _, f := range files {
		part, err := w.CreateFormFile(f.field, f.filename)
		if err != nil {
			t.Fatalf("CreateFormFile: %v", err)
		}
		if _, err := part.Write([]byte(f.content)); err != nil {
			t.Fatalf("Write part: %v", err)
		}
	}
	if err := w.Close(); err != nil {
		t.Fatalf("Close writer: %v", err)
	}
	return w.FormDataContentType(), &body
}

func newMultipartReq(t *testing.T, contentType string, body *bytes.Buffer) *http.Request {
	t.Helper()
	req := httptest.NewRequest("POST", "/upload", body)
	req.Header.Set("Content-Type", contentType)
	return req
}

func TestUploadParse(t *testing.T) {
	t.Run("extrae un archivo del multipart", func(t *testing.T) {
		ct, body := buildMultipart(t, []struct{ field, filename, content string }{
			{"file", "a.txt", "hello"},
		})
		req := newMultipartReq(t, ct, body)

		got, err := UploadParse(req, 1<<20)
		if err != nil {
			t.Fatalf("UploadParse: %v", err)
		}
		if len(got) != 1 {
			t.Fatalf("got %d files, want 1", len(got))
		}
		if got[0].Filename != "a.txt" {
			t.Errorf("got Filename %q", got[0].Filename)
		}
		if got[0].Size != 5 {
			t.Errorf("got Size %d, want 5", got[0].Size)
		}
		buf, _ := io.ReadAll(got[0].Content)
		if string(buf) != "hello" {
			t.Errorf("got content %q, want hello", buf)
		}
	})

	t.Run("extrae multiples archivos", func(t *testing.T) {
		ct, body := buildMultipart(t, []struct{ field, filename, content string }{
			{"a", "1.txt", "uno"},
			{"b", "2.txt", "dos"},
		})
		req := newMultipartReq(t, ct, body)

		got, err := UploadParse(req, 1<<20)
		if err != nil {
			t.Fatalf("UploadParse: %v", err)
		}
		if len(got) != 2 {
			t.Fatalf("got %d files, want 2", len(got))
		}
	})

	t.Run("rechaza content-type no multipart", func(t *testing.T) {
		req := httptest.NewRequest("POST", "/upload", strings.NewReader("x"))
		req.Header.Set("Content-Type", "application/json")
		_, err := UploadParse(req, 1<<20)
		if err == nil || !strings.Contains(err.Error(), "no es multipart") {
			t.Errorf("got %v, want error de content-type", err)
		}
	})

	t.Run("respeta maxSize", func(t *testing.T) {
		ct, body := buildMultipart(t, []struct{ field, filename, content string }{
			{"file", "big.bin", strings.Repeat("x", 1024)},
		})
		req := newMultipartReq(t, ct, body)
		_, err := UploadParse(req, 100) // demasiado pequeno
		if err == nil {
			t.Errorf("got nil err, want max bytes error")
		}
	})
}