package main

import (
	"context"
	"fmt"
	"regexp"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestSeriesPagination pins the SSR series-page pagination contract
// (2026-10-19 paginator fix). The /series page renders its grid and
// paginator entirely server-side (templates/series.templ); page state
// lives in the ?page= query param. The fixture mirrors a prod bulk
// import: 30 series whose items share ONE identical created_at (a single
// transaction's NOW()), which historically left the ORDER BY tied — the
// tiebreaker (library_id, series) makes pages deterministic.
func TestSeriesPagination(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping integration test in short mode")
	}
	setup := setupTestServer(t)

	libID := createTestLibraryWithFolder(t, setup.Server, setup.Token, "Test Pagination Library", false)

	ctx := context.Background()
	const totalSeries = 30
	for i := 1; i <= totalSeries; i++ {
		_, err := setup.DBPool.Exec(ctx,
			`INSERT INTO media_items (library_id, title, file_path, series, created_at, imported_at, updated_at)
			 VALUES ($1, $2, $3, $4, '2026-01-01 00:00:00+00', '2026-01-01 00:00:00+00', '2026-01-01 00:00:00+00')`,
			libID, fmt.Sprintf("Pagination Probe Book %02d", i),
			fmt.Sprintf("/tmp/test-pagination/book-%02d.epub", i),
			fmt.Sprintf("Pagination Probe Series %02d", i),
		)
		require.NoError(t, err)
	}
	t.Cleanup(func() {
		_, _ = setup.DBPool.Exec(ctx, "DELETE FROM libraries WHERE id = $1", libID)
	})

	// templ separates dynamic text segments with HTML comments; strip them
	// so plain regexes work on names and the page chip.
	stripComments := func(html string) string {
		return regexp.MustCompile(`<!--.*?-->`).ReplaceAllString(html, "")
	}
	seriesNames := func(html string) map[string]bool {
		names := map[string]bool{}
		for _, m := range regexp.MustCompile(`<h3[^>]*>([^<]+)</h3>`).FindAllStringSubmatch(stripComments(html), -1) {
			names[strings.TrimSpace(m[1])] = true
		}
		return names
	}
	pageChip := func(html string) string {
		m := regexp.MustCompile(`Page\s+(\d+)\s+of\s+(\d+)`).FindStringSubmatch(stripComments(html))
		if m == nil {
			return ""
		}
		return fmt.Sprintf("Page %s of %s", m[1], m[2])
	}

	perPage := 24 // internal/router/frontend.go perSeriesPage

	t.Run("page1 defaults and next link", func(t *testing.T) {
		code, body := ssrGet(t, setup.Server.URL+"/series?library_id="+libID, setup.Token)
		require.Equal(t, 200, code)

		assert.Equal(t, fmt.Sprintf("Page 1 of 2"), pageChip(body))
		names := seriesNames(body)
		assert.Len(t, names, perPage, "page 1 renders exactly 24 cards")
		assert.Contains(t, names, "Pagination Probe Series 01", "deterministic order: page 1 starts at the first series")
		assert.Contains(t, names, fmt.Sprintf("Pagination Probe Series %02d", perPage), "page 1 ends at the 24th series")
		assert.NotContains(t, names, fmt.Sprintf("Pagination Probe Series %02d", perPage+1), "page 1 must not leak page-2 rows")

		assert.NotContains(t, body, "Previous", "no Previous link on page 1")
		// templ HTML-escapes & as &amp; inside attribute values.
		assert.Contains(t, body, fmt.Sprintf(`href="/series?library_id=%s&amp;page=2"`, libID), "Next link carries library_id and page")
	})

	t.Run("page2 is disjoint and terminal", func(t *testing.T) {
		code, body := ssrGet(t, setup.Server.URL+"/series?library_id="+libID+"&page=2", setup.Token)
		require.Equal(t, 200, code)

		assert.Equal(t, "Page 2 of 2", pageChip(body))
		names := seriesNames(body)
		assert.Len(t, names, totalSeries-perPage, "page 2 renders the remainder")

		code1, body1 := ssrGet(t, setup.Server.URL+"/series?library_id="+libID+"&page=1", setup.Token)
		require.Equal(t, 200, code1)
		page1 := seriesNames(body1)

		for name := range names {
			assert.NotContains(t, page1, name, "pages must be disjoint even with fully tied created_at")
		}
		assert.NotContains(t, body, "Next", "no Next link on the last page")
		assert.Contains(t, body, fmt.Sprintf(`href="/series?library_id=%s&amp;page=1"`, libID), "Previous link carries library_id and page")
	})

	t.Run("missing page param defaults to page 1", func(t *testing.T) {
		code, body := ssrGet(t, setup.Server.URL+"/series?library_id="+libID, setup.Token)
		require.Equal(t, 200, code)
		assert.Equal(t, "Page 1 of 2", pageChip(body))
	})

	t.Run("invalid page param falls back to page 1", func(t *testing.T) {
		for _, bad := range []string{"0", "-3", "two"} {
			code, body := ssrGet(t, setup.Server.URL+"/series?library_id="+libID+"&page="+bad, setup.Token)
			require.Equal(t, 200, code, "page=%s", bad)
			assert.Equal(t, "Page 1 of 2", pageChip(body), "page=%s must clamp to page 1", bad)
		}
	})
}