package store

import (
	"strings"
	"testing"
	"testing/fstest"
)

func TestParseMigrationVersion(t *testing.T) {
	cases := []struct {
		name    string
		want    int
		wantErr string
	}{
		{"0001_initial.sql", 1, ""},
		{"0042_add_oauth_clients.sql", 42, ""},
		{"0001.sql", 0, "expected NNNN_name.sql"},       // no underscore
		{"_orphan.sql", 0, "expected NNNN_name.sql"},    // empty version
		{"abc_notnumeric.sql", 0, "non-numeric version"}, // not a number
		{"0000_zero.sql", 0, "version must be > 0"},     // zero rejected
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			got, err := parseMigrationVersion(tc.name)
			switch {
			case tc.wantErr == "" && err != nil:
				t.Errorf("unexpected error: %v", err)
			case tc.wantErr != "" && err == nil:
				t.Errorf("expected error containing %q, got nil", tc.wantErr)
			case tc.wantErr != "" && !strings.Contains(err.Error(), tc.wantErr):
				t.Errorf("error %q does not contain %q", err, tc.wantErr)
			case tc.wantErr == "" && got != tc.want:
				t.Errorf("got %d, want %d", got, tc.want)
			}
		})
	}
}

func TestLoadMigrations_SortsByVersion(t *testing.T) {
	fsys := fstest.MapFS{
		"m/0003_c.sql": {Data: []byte("-- c")},
		"m/0001_a.sql": {Data: []byte("-- a")},
		"m/0002_b.sql": {Data: []byte("-- b")},
	}
	got, err := loadMigrations(fsys, "m")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(got) != 3 {
		t.Fatalf("got %d migrations, want 3", len(got))
	}
	for i, want := range []int{1, 2, 3} {
		if got[i].version != want {
			t.Errorf("migrations[%d].version = %d, want %d", i, got[i].version, want)
		}
	}
}

func TestLoadMigrations_SkipsNonSQL(t *testing.T) {
	fsys := fstest.MapFS{
		"m/0001_a.sql": {Data: []byte("-- a")},
		"m/README.md":  {Data: []byte("ignore me")},
		"m/notes.txt":  {Data: []byte("ignore me too")},
	}
	got, err := loadMigrations(fsys, "m")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(got) != 1 {
		t.Errorf("got %d migrations, want 1 (non-.sql must be skipped)", len(got))
	}
}

func TestLoadMigrations_RejectsDuplicateVersion(t *testing.T) {
	fsys := fstest.MapFS{
		"m/0001_a.sql": {Data: []byte("-- a")},
		"m/0001_b.sql": {Data: []byte("-- b")},
	}
	_, err := loadMigrations(fsys, "m")
	if err == nil || !strings.Contains(err.Error(), "duplicate migration version 1") {
		t.Errorf("want duplicate-version error, got %v", err)
	}
}

func TestLoadMigrations_RejectsBadFilename(t *testing.T) {
	fsys := fstest.MapFS{
		"m/nogood.sql": {Data: []byte("-- bad")},
	}
	_, err := loadMigrations(fsys, "m")
	if err == nil || !strings.Contains(err.Error(), "expected NNNN_name.sql") {
		t.Errorf("want bad-filename error, got %v", err)
	}
}

func TestLoadMigrations_MissingDir(t *testing.T) {
	_, err := loadMigrations(fstest.MapFS{}, "nope")
	if err == nil || !strings.Contains(err.Error(), "read migrations dir") {
		t.Errorf("want missing-dir error, got %v", err)
	}
}