package api

import (
	"bytes"
	"encoding/json"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func testServerWithDrops(t *testing.T) (*Server, string) {
	t.Helper()
	srv, _ := testServer(t)
	dropsDir := t.TempDir()
	srv.SetDropsDir(dropsDir)
	return srv, dropsDir
}

func TestHandleListDrops_Empty(t *testing.T) {
	srv, _ := testServerWithDrops(t)

	req := httptest.NewRequest("GET", "/api/drops", nil)
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("want 200, got %d", rec.Code)
	}

	var files []map[string]interface{}
	if err := json.NewDecoder(rec.Body).Decode(&files); err != nil {
		t.Fatalf("decode response: %v", err)
	}
	if len(files) != 0 {
		t.Errorf("want empty list, got %d entries", len(files))
	}
}

func TestHandleListDrops_WithFile(t *testing.T) {
	srv, dropsDir := testServerWithDrops(t)

	// Create a file in the drops dir.
	if err := os.WriteFile(filepath.Join(dropsDir, "hello.txt"), []byte("world"), 0600); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("GET", "/api/drops", nil)
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("want 200, got %d: %s", rec.Code, rec.Body.String())
	}

	var files []map[string]interface{}
	if err := json.NewDecoder(rec.Body).Decode(&files); err != nil {
		t.Fatalf("decode response: %v", err)
	}
	if len(files) != 1 {
		t.Fatalf("want 1 file, got %d", len(files))
	}
	if files[0]["name"] != "hello.txt" {
		t.Errorf("name: want %q, got %v", "hello.txt", files[0]["name"])
	}
}

func TestHandlePostDrop_Multipart(t *testing.T) {
	srv, dropsDir := testServerWithDrops(t)

	var buf bytes.Buffer
	w := multipart.NewWriter(&buf)
	fw, err := w.CreateFormFile("file", "test.txt")
	if err != nil {
		t.Fatal(err)
	}
	fw.Write([]byte("hello world")) //nolint:errcheck
	w.Close()

	req := httptest.NewRequest("POST", "/api/drops", &buf)
	req.Header.Set("Content-Type", w.FormDataContentType())
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusCreated {
		t.Fatalf("want 201, got %d: %s", rec.Code, rec.Body.String())
	}

	var resp map[string]interface{}
	if err := json.NewDecoder(rec.Body).Decode(&resp); err != nil {
		t.Fatalf("decode response: %v", err)
	}
	if resp["name"] != "test.txt" {
		t.Errorf("name: want %q, got %v", "test.txt", resp["name"])
	}

	// Verify file was created on disk.
	content, err := os.ReadFile(filepath.Join(dropsDir, "test.txt"))
	if err != nil {
		t.Fatalf("reading uploaded file: %v", err)
	}
	if string(content) != "hello world" {
		t.Errorf("content: want %q, got %q", "hello world", content)
	}
}

func TestHandleGetDrop_Download(t *testing.T) {
	srv, dropsDir := testServerWithDrops(t)

	if err := os.WriteFile(filepath.Join(dropsDir, "download.txt"), []byte("download me"), 0600); err != nil {
		t.Fatal(err)
	}

	req := httptest.NewRequest("GET", "/api/drops/download.txt", nil)
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("want 200, got %d", rec.Code)
	}

	cd := rec.Header().Get("Content-Disposition")
	if !strings.Contains(cd, "attachment") {
		t.Errorf("want Content-Disposition: attachment, got %q", cd)
	}
	if rec.Body.String() != "download me" {
		t.Errorf("body: want %q, got %q", "download me", rec.Body.String())
	}
}

func TestHandleGetDrop_PathTraversal(t *testing.T) {
	srv, _ := testServerWithDrops(t)

	// Attempt path traversal — should be rejected.
	req := httptest.NewRequest("GET", "/api/drops/..%2Fetc%2Fpasswd", nil)
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	// The Go net/http router will handle %2F-encoded slashes as literal characters,
	// so the filename becomes "../etc/passwd". Our handler should reject it.
	if rec.Code == http.StatusOK {
		t.Error("expected non-200 for path traversal attempt")
	}
}

func TestHandleGetDrop_NotFound(t *testing.T) {
	srv, _ := testServerWithDrops(t)

	req := httptest.NewRequest("GET", "/api/drops/notexist.txt", nil)
	rec := httptest.NewRecorder()
	srv.mux.ServeHTTP(rec, req)

	if rec.Code != http.StatusNotFound {
		t.Fatalf("want 404, got %d", rec.Code)
	}
}