# go-migrate

A PostgreSQL schema migration tool that generates and applies migrations by comparing your desired schema (SQL files) with the current database state.

## Features

- **Schema comparison**: Compare your desired schema against the live database
- **Migration generation**: Automatically generate SQL migration statements
- **Migration application**: Apply migrations directly to the database
- **Type support**: Handles tables, columns, indexes, foreign keys, enums, and constraints

## Installation

### As a Library

```bash
go get git.petrovv.com/go-migrate
```

### CLI Tool

```bash
go install git.petrovv.com/go-migrate/cmd/go-migrate@latest
```

## Usage

### Library

```go
import "git.petrovv.com/go-migrate"

ctx := context.Background()
db, _ := pgxpool.New(ctx, "postgres://user:pass@localhost:5432/db")

// Generate migrations
migrations, err := migrate.GetMigrations(ctx, db, "schema/")
for _, m := range migrations {
    fmt.Println(m)
}

// Or use LoadDesiredSchema and CompareSchemas for more control
desired, _ := migrate.LoadDesiredSchema("schema/")
current, _ := migrate.GetCurrentSchema(ctx, db)
migrations = migrate.CompareSchemas(current, desired)
```

### CLI

```bash
# Generate migration SQL
go-migrate -cmd=generate -dir=schema

# Apply migrations
go-migrate -cmd=apply -dir=schema
```

**Flags:**
- `-dir`: Directory containing schema SQL files (default: `schema`)
- `-cmd`: `generate` or `apply`

## Schema Files

Place your desired schema SQL files in a directory (e.g., `schema/`). Files are loaded alphabetically.

Example `schema/01_users.sql`:
```sql
CREATE TABLE users (
    id BIGSERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT NOT NULL UNIQUE
);

CREATE INDEX idx_users_name ON users (name);
```

## Environment Variables

For the CLI, database connection can be configured via environment variables or `.env` file:

```
DB_USER=postgres
DB_PASS=password
DB_HOST=localhost
DB_PORT=5432
DB_NAME=mydb
```