package server

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/gin-gonic/gin"
)

func setupTestContext() (*httptest.ResponseRecorder, *gin.Context) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	return w, c
}

func parseResponse(t *testing.T, w *httptest.ResponseRecorder) APIResponse {
	t.Helper()
	var resp APIResponse
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("failed to parse response body: %v", err)
	}
	return resp
}

func TestOK(t *testing.T) {
	w, c := setupTestContext()
	OK(c, map[string]string{"msg": "hello"})

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if !resp.Success {
		t.Fatal("expected success=true")
	}
}

func TestCreated(t *testing.T) {
	w, c := setupTestContext()
	Created(c, map[string]int{"id": 1})

	if w.Code != http.StatusCreated {
		t.Fatalf("expected 201, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if !resp.Success {
		t.Fatal("expected success=true")
	}
}

func TestBadRequest(t *testing.T) {
	w, c := setupTestContext()
	BadRequest(c, "invalid input")

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if resp.Success {
		t.Fatal("expected success=false")
	}
	if resp.Error != "invalid input" {
		t.Fatalf("expected error 'invalid input', got '%s'", resp.Error)
	}
}

func TestNotFound(t *testing.T) {
	w, c := setupTestContext()
	NotFound(c, "resource missing")

	if w.Code != http.StatusNotFound {
		t.Fatalf("expected 404, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if resp.Success {
		t.Fatal("expected success=false")
	}
	if resp.Error != "resource missing" {
		t.Fatalf("expected error 'resource missing', got '%s'", resp.Error)
	}
}

func TestInternalError(t *testing.T) {
	w, c := setupTestContext()
	InternalError(c, "something broke")

	if w.Code != http.StatusInternalServerError {
		t.Fatalf("expected 500, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if resp.Success {
		t.Fatal("expected success=false")
	}
	if resp.Error != "something broke" {
		t.Fatalf("expected error 'something broke', got '%s'", resp.Error)
	}
}

func TestErrorWithStatus(t *testing.T) {
	w, c := setupTestContext()
	ErrorWithStatus(c, http.StatusConflict, "already exists")

	if w.Code != http.StatusConflict {
		t.Fatalf("expected 409, got %d", w.Code)
	}
	resp := parseResponse(t, w)
	if resp.Success {
		t.Fatal("expected success=false")
	}
	if resp.Error != "already exists" {
		t.Fatalf("expected error 'already exists', got '%s'", resp.Error)
	}
}

func TestParseRangeStandard(t *testing.T) {
	tests := []struct {
		rangeHeader string
		fileSize    int64
		wantStart   int64
		wantEnd     int64
		wantErr     bool
	}{
		{"bytes=0-1023", 10000, 0, 1023, false},
		{"bytes=1024-", 10000, 1024, 9999, false},
		{"bytes=-1024", 10000, 8976, 9999, false},
		{"bytes=0-0", 10000, 0, 0, false},
		{"bytes=9999-", 10000, 9999, 9999, false},
	}
	for _, tt := range tests {
		start, end, err := ParseRange(tt.rangeHeader, tt.fileSize)
		if (err != nil) != tt.wantErr {
			t.Errorf("ParseRange(%q, %d) error = %v, wantErr %v", tt.rangeHeader, tt.fileSize, err, tt.wantErr)
			continue
		}
		if !tt.wantErr {
			if start != tt.wantStart || end != tt.wantEnd {
				t.Errorf("ParseRange(%q, %d) = (%d, %d), want (%d, %d)", tt.rangeHeader, tt.fileSize, start, end, tt.wantStart, tt.wantEnd)
			}
		}
	}
}

func TestParseRangeInvalidAndMultiPart(t *testing.T) {
	tests := []struct {
		rangeHeader string
		fileSize    int64
	}{
		{"", 10000},
		{"bytes=9999-0", 10000},
		{"bytes=20000-", 10000},
		{"bytes=0-100,200-300", 10000},
		{"bytes=0-100, 400-500", 10000},
		{"bytes=", 10000},
		{"chars=0-100", 10000},
	}
	for _, tt := range tests {
		_, _, err := ParseRange(tt.rangeHeader, tt.fileSize)
		if err == nil {
			t.Errorf("ParseRange(%q, %d) expected error, got nil", tt.rangeHeader, tt.fileSize)
		}
	}
}

func TestParseRangeEdgeCases(t *testing.T) {
	start, end, err := ParseRange("bytes=0-99999", 10000)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if end != 9999 {
		t.Errorf("end = %d, want 9999 (clamped to fileSize-1)", end)
	}
	if start != 0 {
		t.Errorf("start = %d, want 0", start)
	}
}