package database

import (
	"context"
	"database/sql"
	"testing"

	_ "modernc.org/sqlite" // SQLite driver registration
)

func TestParseMigrationVersion(t *testing.T) {
	tests := []struct {
		name     string
		filename string
		want     string
		wantErr  bool
	}{
		{
			name:     "version only",
			filename: "001.sql",
			want:     "001",
		},
		{
			name:     "version with description",
			filename: "001_initial_schema.sql",
			want:     "001",
		},
		{
			name:     "multi-digit version",
			filename: "042_add_indexes.sql",
			want:     "042",
		},
		{
			name:     "long version number",
			filename: "00001_long_prefix.sql",
			want:     "00001",
		},
		{
			name:     "description with multiple underscores",
			filename: "003_add_user_auth_tables.sql",
			want:     "003",
		},
		{
			name:     "empty filename",
			filename: ".sql",
			wantErr:  true,
		},
		{
			name:     "leading underscore",
			filename: "_description.sql",
			wantErr:  true,
		},
		{
			name:     "non-numeric version",
			filename: "abc_migration.sql",
			wantErr:  true,
		},
		{
			name:     "mixed alphanumeric version",
			filename: "001a_migration.sql",
			wantErr:  true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := ParseMigrationVersion(tt.filename)
			if tt.wantErr {
				if err == nil {
					t.Errorf("ParseMigrationVersion(%q) expected error, got %q", tt.filename, got)
				}

				return
			}

			if err != nil {
				t.Errorf("ParseMigrationVersion(%q) unexpected error: %v", tt.filename, err)

				return
			}

			if got != tt.want {
				t.Errorf("ParseMigrationVersion(%q) = %q, want %q", tt.filename, got, tt.want)
			}
		})
	}
}

func TestApplyMigrations(t *testing.T) {
	db, err := sql.Open("sqlite", ":memory:")
	if err != nil {
		t.Fatalf("failed to open in-memory database: %v", err)
	}
	defer db.Close()

	// Apply migrations should succeed.
	if err := ApplyMigrations(db); err != nil {
		t.Fatalf("ApplyMigrations failed: %v", err)
	}

	// Verify the schema_migrations table recorded the version.
	var version string

	err = db.QueryRowContext(context.Background(),
		"SELECT version FROM schema_migrations LIMIT 1",
	).Scan(&version)
	if err != nil {
		t.Fatalf("failed to query schema_migrations: %v", err)
	}

	if version != "001" {
		t.Errorf("expected version %q, got %q", "001", version)
	}

	// Verify a table from the migration exists (source_content).
	var tableName string

	err = db.QueryRowContext(context.Background(),
		"SELECT name FROM sqlite_master WHERE type='table' AND name='source_content'",
	).Scan(&tableName)
	if err != nil {
		t.Fatalf("expected source_content table to exist: %v", err)
	}
}

func TestApplyMigrationsIdempotent(t *testing.T) {
	db, err := sql.Open("sqlite", ":memory:")
	if err != nil {
		t.Fatalf("failed to open in-memory database: %v", err)
	}
	defer db.Close()

	// Apply twice should succeed (idempotent).
	if err := ApplyMigrations(db); err != nil {
		t.Fatalf("first ApplyMigrations failed: %v", err)
	}

	if err := ApplyMigrations(db); err != nil {
		t.Fatalf("second ApplyMigrations failed: %v", err)
	}

	// Should still have exactly one migration recorded.
	var count int

	err = db.QueryRowContext(context.Background(),
		"SELECT COUNT(*) FROM schema_migrations",
	).Scan(&count)
	if err != nil {
		t.Fatalf("failed to count schema_migrations: %v", err)
	}

	if count != 1 {
		t.Errorf("expected 1 migration record, got %d", count)
	}
}