package api

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/gin-gonic/gin"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestClassifyDBError 驗證 pgx error → (status, code) 映射（塊 5.4）。
func TestClassifyDBError(t *testing.T) {
	cases := []struct {
		name       string
		err        error
		wantStatus int
		wantCode   string
	}{
		{
			name:       "context deadline → 503",
			err:        context.DeadlineExceeded,
			wantStatus: http.StatusServiceUnavailable,
			wantCode:   ErrCodeServiceUnavailable,
		},
		{
			name:       "context canceled → 503",
			err:        context.Canceled,
			wantStatus: http.StatusServiceUnavailable,
			wantCode:   ErrCodeServiceUnavailable,
		},
		{
			name:       "wrapped deadline → 503",
			err:        fmt.Errorf("device: pg List: %w", context.DeadlineExceeded),
			wantStatus: http.StatusServiceUnavailable,
			wantCode:   ErrCodeServiceUnavailable,
		},
		{
			name:       "unique violation 23505 → 409",
			err:        &pgconn.PgError{Code: "23505", Message: "duplicate key value"},
			wantStatus: http.StatusConflict,
			wantCode:   ErrCodeConflict,
		},
		{
			name:       "wrapped unique violation → 409",
			err:        fmt.Errorf("device: pg Save: %w", &pgconn.PgError{Code: "23505"}),
			wantStatus: http.StatusConflict,
			wantCode:   ErrCodeConflict,
		},
		{
			name:       "other PG error (syntax) → 500",
			err:        &pgconn.PgError{Code: "42601", Message: "syntax error"},
			wantStatus: http.StatusInternalServerError,
			wantCode:   ErrCodeInternalError,
		},
		{
			name:       "connect error → 503",
			err:        &pgconn.ConnectError{Config: &pgconn.Config{}},
			wantStatus: http.StatusServiceUnavailable,
			wantCode:   ErrCodeServiceUnavailable,
		},
		{
			name:       "unknown error → 500",
			err:        errors.New("something unexpected"),
			wantStatus: http.StatusInternalServerError,
			wantCode:   ErrCodeInternalError,
		},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			cls := classifyDBError(tc.err)
			assert.Equal(t, tc.wantStatus, cls.status)
			assert.Equal(t, tc.wantCode, cls.code)
			// message 一律是通用字串，不含 raw error 內容
			assert.NotEmpty(t, cls.message)
		})
	}
}

// TestWriteDBError_NoRawLeak 驗證 WriteDBError 不把 raw DB error 寫進 response body（收塊 3 M1）。
func TestWriteDBError_NoRawLeak(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)

	rawErr := &pgconn.PgError{Code: "42601",
		Message: "syntax error at or near SELECT",
		Detail:  "secret-schema-detail",
		Hint:    "internal hint that should not leak",
	}
	WriteDBError(c, nil, "list devices", rawErr)

	require.Equal(t, http.StatusInternalServerError, w.Code)
	body := w.Body.String()
	// 對外只有通用 code/message，raw error 的細節不得出現
	assert.Contains(t, body, ErrCodeInternalError)
	assert.NotContains(t, body, "syntax error")
	assert.NotContains(t, body, "secret-schema-detail")
	assert.NotContains(t, body, "internal hint")
}

// TestWriteDBError_PGDown503 驗證 PG down（connect error）→ 503 + SERVICE_UNAVAILABLE。
func TestWriteDBError_PGDown503(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)

	WriteDBError(c, nil, "get model", &pgconn.ConnectError{Config: &pgconn.Config{}})

	require.Equal(t, http.StatusServiceUnavailable, w.Code)
	assert.Contains(t, w.Body.String(), ErrCodeServiceUnavailable)
}