package commits

import (
	"strings"
	"testing"
)

// FuzzParse verifies that the parser never panics and always returns a valid Type.
func FuzzParse(f *testing.F) {
	// Seed corpus: representative conventional commit messages
	seeds := []string{
		"feat: add OAuth2 login",
		"fix: correct null pointer",
		"feat!: remove legacy API",
		"feat(auth): add login\n\nBREAKING CHANGE: old endpoint removed",
		"chore: update deps",
		"Feat:missing space",
		"FIX(scope)!: mixed case breaking",
		"",
		"\x00",
		"BREAKING CHANGE: bare footer",
		"not a conventional commit at all",
		"feat: \n\n body only",
		strings.Repeat("a", 4096),
	}
	for _, s := range seeds {
		f.Add(s)
	}

	f.Fuzz(func(t *testing.T, msg string) {
		result := Parse(msg)
		if result < TypeNone || result > TypeBreaking {
			t.Errorf("Parse(%q) returned out-of-range type %d", msg, result)
		}
	})
}

func TestExtractSubject(t *testing.T) {
	cases := []struct {
		header string
		want   string
	}{
		{"feat: add login", "add login"},
		{"feat(auth): add OAuth2", "add OAuth2"},
		{"feat!: remove API", "remove API"},
		{"FIX:typo", "typo"},
		{"plain message", "plain message"},
	}
	for _, c := range cases {
		got := ExtractSubject(c.header)
		if got != c.want {
			t.Errorf("ExtractSubject(%q) = %q, want %q", c.header, got, c.want)
		}
	}
}

func TestGroup(t *testing.T) {
	messages := []string{
		"feat: add login",
		"fix: patch null pointer",
		"feat!: remove legacy API",
		"chore: update deps",
		"fix: handle empty response",
	}
	breaking, feats, fixes := Group(messages)
	if len(breaking) != 1 || breaking[0] != "remove legacy API" {
		t.Errorf("breaking = %v, want [remove legacy API]", breaking)
	}
	if len(feats) != 1 || feats[0] != "add login" {
		t.Errorf("feats = %v, want [add login]", feats)
	}
	if len(fixes) != 2 {
		t.Errorf("fixes = %v, want 2 items", fixes)
	}
}

func TestReleasableSet(t *testing.T) {
	all := ReleasableSet(nil)
	if !all[TypeFix] || !all[TypeFeat] || !all[TypeBreaking] {
		t.Error("nil input should return all three types")
	}
	only := ReleasableSet([]string{"fix"})
	if !only[TypeFix] || only[TypeFeat] || only[TypeBreaking] {
		t.Errorf("fix-only set: %v", only)
	}
	onlyFeat := ReleasableSet([]string{"feat"})
	if onlyFeat[TypeFix] || !onlyFeat[TypeFeat] || onlyFeat[TypeBreaking] {
		t.Errorf("feat-only set: %v", onlyFeat)
	}
	onlyBreaking := ReleasableSet([]string{"breaking"})
	if onlyBreaking[TypeFix] || onlyBreaking[TypeFeat] || !onlyBreaking[TypeBreaking] {
		t.Errorf("breaking-only set: %v", onlyBreaking)
	}
}

func TestTypeString(t *testing.T) {
	cases := []struct {
		t    Type
		want string
	}{
		{TypeNone, "none"},
		{TypeFix, "fix"},
		{TypeFeat, "feat"},
		{TypeBreaking, "breaking"},
		{Type(99), "none"}, // unknown → default
	}
	for _, c := range cases {
		if got := c.t.String(); got != c.want {
			t.Errorf("Type(%d).String() = %q, want %q", c.t, got, c.want)
		}
	}
}

func TestParse(t *testing.T) {
	cases := []struct {
		msg  string
		want Type
	}{
		// standard cases
		{"feat: add login page", TypeFeat},
		{"fix: correct null pointer", TypeFix},
		{"chore: update deps", TypeNone},
		{"docs: update README", TypeNone},

		// non-strict: case-insensitive
		{"Feat: add login page", TypeFeat},
		{"FIX: correct null pointer", TypeFix},
		{"FEAT: add login", TypeFeat},

		// non-strict: missing space after colon
		{"feat:add login", TypeFeat},
		{"fix:correct null pointer", TypeFix},

		// with scope
		{"feat(auth): add OAuth2", TypeFeat},
		{"fix(db): prevent deadlock", TypeFix},

		// breaking change via !
		{"feat!: remove legacy API", TypeBreaking},
		{"fix!: change response format", TypeBreaking},
		{"feat(api)!: rename endpoint", TypeBreaking},

		// breaking change via footer
		{"feat: new API\n\nBREAKING CHANGE: old API removed", TypeBreaking},
		{"refactor: cleanup\n\nBREAKING CHANGE: interface changed", TypeBreaking},

		// unparseable — silently ignored
		{"WIP", TypeNone},
		{"Merge branch 'main' into release/1.2", TypeNone},
		{"", TypeNone},
		{"fix a bug without colon", TypeNone},
	}

	for _, c := range cases {
		got := Parse(c.msg)
		if got != c.want {
			t.Errorf("Parse(%q) = %s, want %s", c.msg, got, c.want)
		}
	}
}