# config

Typed configuration loading with [viper](https://github.com/spf13/viper) and [validator](https://github.com/go-playground/validator).

## Install

```bash
go get gitea.auvem.com/go-toolkit/config
```

## Quick start

```go
type Schema struct {
    AppName string `mapstructure:"appName" validate:"required"`
}

dir, err := config.RootDir(".env.yml", 1)
if err != nil {
    log.Fatal(err)
}

m := config.NewManager[Schema](".env", "yaml", dir).WithOpts(&config.ManagerOpts[Schema]{
    EnvPrefix: "MYAPP",
    PostLoad: func(cfg *Schema) error {
        // derived fields — validated again after PostLoad
        return nil
    },
})

if err := m.Load(); err != nil {
    log.Fatal(err)
}

cfg := m.C() // or m.Config()
_ = cfg.AppName
```

## Load vs C

- `Load()` returns errors explicitly — use in `main` during startup
- `C()` and `Config()` lazy-load and panic on failure — convenient after startup

## PostLoad hooks

PostLoad runs after the first validation pass. The schema is **re-validated** after PostLoad so derived fields cannot bypass constraints.

## RootDir

`RootDir(name, depth)` returns `(string, error)`. `MustRootDir` panics on failure (for package-level `var` initialization).

## Breaking changes (V1)

| Before | After |
|--------|-------|
| `PostLoad func(*Manager[T])` | `PostLoad func(*T)` |
| `PreLoad func(*Manager[T])` | `PreLoad func(*T)` |
| `Manager.R` field | use `C()` / hook `*T` parameter |
| `RootDir(...) string` (panic) | `RootDir(...) (string, error)`; use `MustRootDir` for panic |

## Companion types

Configuration structs in [dbx](https://gitea.auvem.com/go-toolkit/dbx) and [courier](https://gitea.auvem.com/go-toolkit/courier) include mapstructure/validate tags compatible with this package.