package stringutil

import (
	"testing"
	"time"
)

func TestRemoveItemByValue(t *testing.T) {
	tests := []struct {
		name     string
		input    []string
		remove   string
		expected []string
	}{
		{
			name:     "empty slice",
			input:    []string{},
			remove:   "a",
			expected: []string{},
		},
		{
			name:     "no matches",
			input:    []string{"b", "c"},
			remove:   "a",
			expected: []string{"b", "c"},
		},
		{
			name:     "single match",
			input:    []string{"a", "b", "c"},
			remove:   "b",
			expected: []string{"a", "c"},
		},
		{
			name:     "multiple matches",
			input:    []string{"a", "b", "a", "c", "a"},
			remove:   "a",
			expected: []string{"b", "c"},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := RemoveItemByValue(tt.input, tt.remove)
			if len(result) != len(tt.expected) {
				t.Errorf("got len %d, want %d", len(result), len(tt.expected))
			}
			for i := range result {
				if result[i] != tt.expected[i] {
					t.Errorf("at index %d got %s, want %s", i, result[i], tt.expected[i])
				}
			}
		})
	}
}

func TestFormatDuration(t *testing.T) {
	tests := []struct {
		name           string
		duration       time.Duration
		includeSeconds bool
		expected       string
	}{
		{
			name:           "zero duration with seconds",
			duration:       0,
			includeSeconds: true,
			expected:       "0 minutes",
		},
		{
			name:           "hours only",
			duration:       2 * time.Hour,
			includeSeconds: false,
			expected:       "2 hours 0 minutes",
		},
		{
			name:           "hours and minutes",
			duration:       2*time.Hour + 30*time.Minute,
			includeSeconds: false,
			expected:       "2 hours 30 minutes",
		},
		{
			name:           "full duration with seconds",
			duration:       2*time.Hour + 30*time.Minute + 15*time.Second,
			includeSeconds: true,
			expected:       "2 hours 30 minutes 15 seconds",
		},
		{
			name:           "full duration without seconds",
			duration:       2*time.Hour + 30*time.Minute + 15*time.Second,
			includeSeconds: false,
			expected:       "2 hours 30 minutes",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := FormatDuration(tt.duration, tt.includeSeconds)
			if result != tt.expected {
				t.Errorf("got %q, want %q", result, tt.expected)
			}
		})
	}
}

func TestExtractConvUUID(t *testing.T) {
	tests := []struct {
		name     string
		email    string
		expected string
	}{
		{
			name:     "valid UUID v4",
			email:    "support+conv-13216cf7-6626-4b0d-a938-46ce65a20701@domain.com",
			expected: "13216cf7-6626-4b0d-a938-46ce65a20701",
		},
		{
			name:     "uppercase UUID v4",
			email:    "support+conv-13216CF7-6626-4B0D-A938-46CE65A20701@domain.com",
			expected: "13216CF7-6626-4B0D-A938-46CE65A20701",
		},
		{
			name:     "no plus addressing",
			email:    "support@domain.com",
			expected: "",
		},
		{
			name:     "non-conv plus addressing",
			email:    "support+other@domain.com",
			expected: "",
		},
		{
			name:     "short non-UUID (user email)",
			email:    "support+conv-21321@domain.com",
			expected: "",
		},
		{
			name:     "invalid UUID format",
			email:    "support+conv-abc123-def456@domain.com",
			expected: "",
		},
		{
			name:     "missing 4 in UUID (invalid v4)",
			email:    "support+conv-13216cf7-6626-ab0d-a938-46ce65a20701@domain.com",
			expected: "",
		},
		{
			name:     "empty string",
			email:    "",
			expected: "",
		},
		{
			name:     "missing @ symbol",
			email:    "support+conv-13216cf7-6626-4b0d-a938-46ce65a20701",
			expected: "",
		},
		{
			name:     "UUID with extra chars",
			email:    "support+conv-13216cf7-6626-4b0d-a938-46ce65a20701-extra@domain.com",
			expected: "",
		},
		{
			name:     "valid UUID different local part",
			email:    "inbox+conv-a1b2c3d4-e5f6-4a7b-8c9d-0e1f2a3b4c5d@example.org",
			expected: "a1b2c3d4-e5f6-4a7b-8c9d-0e1f2a3b4c5d",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := ExtractConvUUID(tt.email)
			if result != tt.expected {
				t.Errorf("ExtractConvUUID(%q) = %q, want %q", tt.email, result, tt.expected)
			}
		})
	}
}

func TestExtractReferenceNumber(t *testing.T) {
	tests := []struct {
		name     string
		subject  string
		expected string
	}{
		{
			name:     "simple reference number",
			subject:  "Test - #392",
			expected: "392",
		},
		{
			name:     "with RE prefix",
			subject:  "RE: Test - #392",
			expected: "392",
		},
		{
			name:     "multiple hashes picks last",
			subject:  "Order #123 - #392",
			expected: "392",
		},
		{
			name:     "no reference number",
			subject:  "Just a regular subject",
			expected: "",
		},
		{
			name:     "hash without number",
			subject:  "Test #abc",
			expected: "",
		},
		{
			name:     "empty string",
			subject:  "",
			expected: "",
		},
		{
			name:     "number without hash",
			subject:  "Test 392",
			expected: "",
		},
		{
			name:     "multiple RE prefixes",
			subject:  "RE: RE: Test - #100",
			expected: "100",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := ExtractReferenceNumber(tt.subject)
			if result != tt.expected {
				t.Errorf("ExtractReferenceNumber(%q) = %q, want %q", tt.subject, result, tt.expected)
			}
		})
	}
}

func TestSanitizeUTF8(t *testing.T) {
	tests := []struct {
		name     string
		input    string
		expected string
	}{
		{"empty", "", ""},
		{"plain ascii unchanged", "Hello, world!", "Hello, world!"},
		{"valid copyright unchanged", "© 2026", "© 2026"},
		{"orphan 0xa9 replaced", "\xa9 2026 Upstox", "� 2026 Upstox"},
		{"nul stripped", "a\x00b", "ab"},
		{"chinese unchanged", "你好世界", "你好世界"},
		{"devanagari unchanged", "नमस्ते", "नमस्ते"},
		{"arabic unchanged", "مرحبا", "مرحبا"},
		{"emoji unchanged", "ok 😀👍", "ok 😀👍"},
		{"accented latin unchanged", "café résumé", "café résumé"},
		{"run of invalid bytes collapses to one replacement", "x\xa9\xa9y", "x�y"},
		{"truncated 3-byte char replaced", "\xe4\xbd", "�"},
		{"lead byte at end replaced", "abc\xc3", "abc�"},
		{"overlong encoding replaced", "x\xc0\x80y", "x�y"},
		{"cp1252 smart quotes replaced", "\x93hi\x94", "�hi�"},
		{"multiple embedded nuls stripped", "a\x00\x00b\x00c", "abc"},
		{"nul and invalid byte combined", "a\x00\xa9b", "a�b"},
		{"valid multibyte preserved around invalid byte", "a你\xa9好b", "a你�好b"},
		{"bom preserved", "\ufeffhi", "\ufeffhi"},
		{"existing replacement char preserved", "a�b", "a�b"},
		{"crlf and tab preserved", "l1\r\nl2\t", "l1\r\nl2\t"},
		{"paired continuation kept, orphan replaced", "é\xa9", "é�"},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := SanitizeUTF8(tt.input); got != tt.expected {
				t.Errorf("SanitizeUTF8(%q) = %q, want %q", tt.input, got, tt.expected)
			}
		})
	}
}

func TestSplitName(t *testing.T) {
	tests := []struct {
		name      string
		input     string
		wantFirst string
		wantLast  string
	}{
		{name: "empty", input: "", wantFirst: "", wantLast: ""},
		{name: "whitespace only", input: "   ", wantFirst: "", wantLast: ""},
		{name: "single name", input: "Cher", wantFirst: "Cher", wantLast: ""},
		{name: "first and last", input: "John Doe", wantFirst: "John", wantLast: "Doe"},
		{name: "middle name", input: "John Michael Doe", wantFirst: "John", wantLast: "Michael Doe"},
		{name: "multi-word surname", input: "Ludwig van der Berg", wantFirst: "Ludwig", wantLast: "van der Berg"},
		{name: "extra spaces", input: "  John   Doe  ", wantFirst: "John", wantLast: "Doe"},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			first, last := SplitName(tt.input)
			if first != tt.wantFirst || last != tt.wantLast {
				t.Errorf("SplitName(%q) = (%q, %q), want (%q, %q)", tt.input, first, last, tt.wantFirst, tt.wantLast)
			}
		})
	}
}

func TestHTML2TextMarkdownLinks(t *testing.T) {
	tests := []struct {
		name string
		html string
		want string
	}{
		{
			name: "link with distinct text becomes a markdown link",
			html: `<p>See <a href="https://example.com/guide">the guide</a> for steps.</p>`,
			want: "See [the guide](https://example.com/guide) for steps.",
		},
		{
			name: "link text equal to url not duplicated",
			html: `<p><a href="https://example.com">https://example.com</a></p>`,
			want: "https://example.com",
		},
		{
			name: "plain text unchanged",
			html: `<p>No links here.</p>`,
			want: "No links here.",
		},
		{
			name: "nested markup inside the anchor flattens to link text",
			html: `<p><a href="https://example.com/x"><strong>Pay</strong> now</a></p>`,
			want: "[Pay now](https://example.com/x)",
		},
		{
			name: "brackets in link text are escaped",
			html: `<p><a href="https://example.com">Docs [beta]</a></p>`,
			want: `[Docs \[beta\]](https://example.com)`,
		},
		{
			name: "url with parentheses is wrapped in angle brackets",
			html: `<p><a href="https://example.com/a(b)">See</a></p>`,
			want: "[See](<https://example.com/a(b)>)",
		},
		{
			name: "anchor without href keeps its text",
			html: `<p><a name="top">Top</a> of page.</p>`,
			want: "Top of page.",
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := HTML2TextMarkdownLinks(tt.html); got != tt.want {
				t.Errorf("got %q, want %q", got, tt.want)
			}
		})
	}
}