package trafficusage

import (
	"fmt"
	"hash/fnv"
	"strings"
	"testing"
	"time"
	"unicode"
)

// adminChildTableName is a verbatim copy of Admin's childTableNameWithPrefix
// (iotlcm-admin-svr internal/logic/trafficusage/traffic_usage.go). It exists so
// the worker rule is asserted against the production reader rule rather than
// against itself: Admin's QueryDaily resolves child tables with this rule, so
// any divergence here would silently hide a card's daily usage.
func adminChildTableName(prefix, value string) string {
	var builder strings.Builder
	builder.WriteString(prefix)
	for _, r := range strings.ToLower(value) {
		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == '_' {
			builder.WriteRune(r)
		}
	}
	name := builder.String()
	if name == prefix || len(name) > 190 {
		hash := fnv.New32a()
		_, _ = hash.Write([]byte(value))
		return fmt.Sprintf("%s%x", prefix, hash.Sum32())
	}
	return name
}

func adminChildTrafficTableName(stable, iccid string) string {
	prefix := "sim_card_usage_m_"
	if stable == "t_sim_card_usage_daily" {
		prefix = "sim_card_usage_d_"
	}
	return adminChildTableName(prefix, iccid)
}

func TestChildTableNameMatchesAdminRule(t *testing.T) {
	longICCID := strings.Repeat("8", 191)
	veryLongICCID := strings.Repeat("89", 120)
	cases := []string{
		"",
		"89860001123456789012",
		"8986-0001",
		"8986 0001",
		"8986.0001",
		"8986/0001",
		"ICCID_8986",
		"8986-0001-中文",
		"中文卡号",
		"____",
		"8986+0001",
		"8986'0001",
		longICCID,
		veryLongICCID,
	}
	for _, stable := range []string{"t_sim_card_usage_daily", "t_sim_card_usage_monthly"} {
		for _, iccid := range cases {
			want := adminChildTrafficTableName(stable, iccid)
			got := childTableName(stable, iccid)
			if got != want {
				t.Errorf("childTableName(%q, %q) = %q, admin rule yields %q", stable, iccid, got, want)
			}
			if !strings.HasPrefix(got, "sim_card_usage_") {
				t.Errorf("childTableName(%q, %q) = %q loses the table prefix", stable, iccid, got)
			}
		}
	}
}

// TestChildTableNameDirtyICCIDSplitsOnce guards the original defect: the old
// worker rule replaced illegal characters with "_" while Admin dropped them, so
// a dirty ICCID could land in a different child table than the reader queried.
func TestChildTableNameDirtyICCIDSplitsOnce(t *testing.T) {
	for _, iccid := range []string{"8986-0001", "8986 0001", "8986.0001"} {
		got := childTableName("t_sim_card_usage_daily", iccid)
		if strings.Contains(got, "__") {
			t.Errorf("childTableName(%q) = %q still substitutes instead of dropping", iccid, got)
		}
		if got != "sim_card_usage_d_89860001" {
			t.Errorf("childTableName(%q) = %q, want the illegal characters dropped", iccid, got)
		}
	}
}

func TestChildTableNameLongIdentifierUsesHashFallback(t *testing.T) {
	iccid := strings.Repeat("8", 191)
	got := childTableName("t_sim_card_usage_daily", iccid)
	if len(got) > 190 {
		t.Fatalf("childTableName kept an over-long name: len=%d", len(got))
	}
	if got != adminChildTrafficTableName("t_sim_card_usage_daily", iccid) {
		t.Fatalf("hash fallback diverged from the admin rule: %q", got)
	}
}

func TestSnapshotDayUsesEndOfDay(t *testing.T) {
	// The dashboard "yesterday top 5" and the diagnosis page both select the
	// 23:59:59.000 row, so the timestamp contract must not drift.
	day := snapshotDay(mustParse(t, "2026-10-09T13:45:00+08:00"))
	if got := day.Format("2006-01-02 15:04:05.000"); got != "2026-10-09 23:59:59.000" {
		t.Fatalf("snapshotDay = %s, want 2026-10-09 23:59:59.000", got)
	}
}

func mustParse(t *testing.T, value string) time.Time {
	t.Helper()
	parsed, err := time.Parse(time.RFC3339, value)
	if err != nil {
		t.Fatalf("parse %q: %v", value, err)
	}
	return parsed
}

// TestSnapshotMonthMatchesAdminRule pins the monthly timestamp contract.
//
// The diagnosis page reads monthly history by ts and groups it with
// ts.Format("2006-01"), while admin's monthStart wrote the end-of-month
// 23:59:59.000 row. A migration that changed this would leave the page reading
// a month that never gets written.
func TestSnapshotMonthMatchesAdminRule(t *testing.T) {
	// adminMonthStart is a verbatim copy of Admin's monthStart
	// (iotlcm-admin-svr internal/logic/trafficusage/traffic_usage.go), despite
	// its name returning the end of the month.
	adminMonthStart := func(tm time.Time) time.Time {
		if tm.IsZero() {
			tm = time.Now()
		}
		return time.Date(tm.Year(), tm.Month()+1, 0, 23, 59, 59, 0, tm.Location())
	}
	location := time.FixedZone("UTC+8", 8*60*60)
	for _, month := range []time.Time{
		time.Date(2026, 9, 1, 0, 0, 0, 0, location),
		time.Date(2026, 2, 1, 0, 0, 0, 0, location),
		time.Date(2026, 12, 1, 0, 0, 0, 0, location),
		// Leap February must land on the 29th.
		time.Date(2024, 2, 1, 0, 0, 0, 0, location),
	} {
		want := adminMonthStart(month).Format("2006-01-02 15:04:05.000")
		got := snapshotMonth(month).Format("2006-01-02 15:04:05.000")
		if got != want {
			t.Errorf("snapshotMonth(%s) = %s, admin rule yields %s", month.Format("2006-01"), got, want)
		}
	}
}