package main

import (
	"testing"
	"time"
)

func TestParse(t *testing.T) {
	// Reference time: 2025-11-19T11:07:13Z
	// Unix: 1763550433
	refTime := time.Date(2025, 11, 19, 11, 7, 13, 0, time.UTC)

	tests := []struct {
		input    string
		expected func() time.Time
		desc     string
	}{
		{
			input: "1763550433",
			expected: func() time.Time {
				return refTime
			},
			desc: "Unix timestamp",
		},
		{
			input: "2025-11-19T11:07:13Z",
			expected: func() time.Time {
				return refTime
			},
			desc: "ISO 8601 UTC",
		},
		{
			input: "2025-11-19T11:07:13",
			expected: func() time.Time {
				return time.Date(2025, 11, 19, 11, 7, 13, 0, time.Local)
			},
			desc: "ISO 8601 Local",
		},
		{
			input: "2025-11-19 11:07:13Z",
			expected: func() time.Time {
				return refTime
			},
			desc: "Date Space Time Z",
		},
		{
			input: "2025-11-19",
			expected: func() time.Time {
				return time.Date(2025, 11, 19, 0, 0, 0, 0, time.Local)
			},
			desc: "Date only Local",
		},
		{
			input: "2025-11-19Z",
			expected: func() time.Time {
				return time.Date(2025, 11, 19, 0, 0, 0, 0, time.UTC)
			},
			desc: "Date only UTC",
		},
		{
			input: "11:07:13",
			expected: func() time.Time {
				now := time.Now()
				return time.Date(now.Year(), now.Month(), now.Day(), 11, 7, 13, 0, time.Local)
			},
			desc: "Time only Local",
		},
		{
			input: "11:07:13Z",
			expected: func() time.Time {
				now := time.Now().In(time.UTC)
				return time.Date(now.Year(), now.Month(), now.Day(), 11, 7, 13, 0, time.UTC)
			},
			desc: "Time only UTC",
		},
	}

	for _, tc := range tests {
		t.Run(tc.desc, func(t *testing.T) {
			res, err := Parse(tc.input)
			if err != nil {
				t.Fatalf("Parse(%q) error: %v", tc.input, err)
			}
			got, err := res.Time()
			if err != nil {
				t.Fatalf("res.Time() error: %v", err)
			}

			want := tc.expected()

			// For "Time only" tests, there might be a slight race condition if the day changes between test execution and expected value generation.
			// But practically it's fine.

			if !got.Truncate(time.Second).Equal(want) {
				t.Errorf("Parse(%q) = %v, want %v", tc.input, got, want)
			}
		})
	}

	t.Run("now", func(t *testing.T) {
		res, err := Parse("now")
		if err != nil {
			t.Fatalf("Parse('now') error: %v", err)
		}
		got, err := res.Time()
		if err != nil {
			t.Fatalf("res.Time() error: %v", err)
		}
		if time.Since(got) > time.Second {
			t.Errorf("Parse('now') = %v, want close to now", got)
		}
	})
}