package web

import (
	"testing"
	"time"

	"github.com/m/projax/store"
)

func TestParsePER(t *testing.T) {
	cases := []struct {
		in       string
		wantBase string
		wantDate string // empty == nil
	}{
		{"dev.projax", "dev.projax", ""},
		{"dev.projax.260515", "dev.projax", "2026-05-15"},
		{"mfin.house1.260515", "mfin.house1", "2026-05-15"},
		// Six-digit but not a valid date → leave unchanged.
		{"foo.260230", "foo.260230", ""},          // Feb 30 doesn't exist
		{"foo.260000", "foo.260000", ""},          // month 00
		{"foo.261301", "foo.261301", ""},          // month 13
		{"foo.999999", "foo.999999", ""},          // not a real date
		// Wrong length → leave unchanged.
		{"foo.bar", "foo.bar", ""},
		{"foo.12345", "foo.12345", ""},
		{"foo.1234567", "foo.1234567", ""},
		// Empty trailing segment.
		{"foo.", "foo.", ""},
		// No dot at all.
		{"260515", "260515", ""},
	}
	for _, tc := range cases {
		gotBase, gotDate := parsePER(tc.in)
		if gotBase != tc.wantBase {
			t.Errorf("parsePER(%q) base = %q, want %q", tc.in, gotBase, tc.wantBase)
		}
		if tc.wantDate == "" {
			if gotDate != nil {
				t.Errorf("parsePER(%q) date = %v, want nil", tc.in, gotDate)
			}
			continue
		}
		want, _ := time.Parse("2006-01-02", tc.wantDate)
		if gotDate == nil || !gotDate.Equal(want) {
			t.Errorf("parsePER(%q) date = %v, want %v", tc.in, gotDate, want)
		}
	}
}

func TestCollisionTag(t *testing.T) {
	cases := []struct {
		n    int
		want string
	}{
		{0, ""},
		{1, "a"},
		{2, "b"},
		{26, "z"},
		{27, "aa"},
		{28, "ab"},
		{52, "az"},
		{53, "ba"},
	}
	for _, tc := range cases {
		if got := collisionTag(tc.n); got != tc.want {
			t.Errorf("collisionTag(%d) = %q, want %q", tc.n, got, tc.want)
		}
	}
}

func TestComputePERsBareThenAB(t *testing.T) {
	d := time.Date(2026, 5, 15, 0, 0, 0, 0, time.UTC)
	d2 := time.Date(2026, 5, 16, 0, 0, 0, 0, time.UTC)
	links := []*store.ItemLink{
		// 2026-05-15 group: 2 entries (sorted by created_at ASC; first bare, second .a)
		{ID: "x1", EventDate: &d, CreatedAt: time.Date(2026, 5, 15, 9, 0, 0, 0, time.UTC)},
		{ID: "x2", EventDate: &d, CreatedAt: time.Date(2026, 5, 15, 10, 0, 0, 0, time.UTC)},
		// 2026-05-16 group: 1 entry (bare).
		{ID: "x3", EventDate: &d2, CreatedAt: time.Date(2026, 5, 16, 9, 0, 0, 0, time.UTC)},
	}
	// Caller invariant: DatedLinks returns event_date DESC, created_at ASC.
	// Test data above is created_at ASC; reverse the date groups to match.
	desc := []*store.ItemLink{links[2], links[0], links[1]}
	rows := computePERs("mfin.house1", desc)
	if len(rows) != 3 {
		t.Fatalf("expected 3 rows, got %d", len(rows))
	}
	if rows[0].PER != "mfin.house1.260516" {
		t.Errorf("row 0 PER = %q", rows[0].PER)
	}
	if rows[1].PER != "mfin.house1.260515" || rows[1].Tag != "" {
		t.Errorf("row 1 should be bare, got PER=%q tag=%q", rows[1].PER, rows[1].Tag)
	}
	if rows[2].PER != "mfin.house1.260515.a" || rows[2].Tag != "a" {
		t.Errorf("row 2 should be .a, got PER=%q tag=%q", rows[2].PER, rows[2].Tag)
	}
}

func TestComputePERsSkipsUndated(t *testing.T) {
	d := time.Date(2026, 5, 15, 0, 0, 0, 0, time.UTC)
	links := []*store.ItemLink{
		{ID: "with", EventDate: &d, CreatedAt: time.Now()},
		{ID: "without", EventDate: nil, CreatedAt: time.Now()},
	}
	rows := computePERs("dev.x", links)
	if len(rows) != 1 || rows[0].Link.ID != "with" {
		t.Errorf("undated link should be skipped, got %v", rows)
	}
}