// Package fromruntime is compose/frombus's StatesReader over a bundle's runtime (the lead, 2026-10-29): the states a
// module's manifest names in `reads` (frombus.StatesReads), read through stdio.State, and a templates archive fetched
// over HTTP. Apart from frombus so that frombus stays pure for the mesh-compose command.
package fromruntime

import (
	"context"
	"fmt"
	"io"
	"net/http"

	stdio "git.novox.be/novox/mesh-sdk/go"
	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
)

// States are a bundle's read states through its runtime.
type States struct{}

// Get is a key's value, false when it has none.
func (States) Get(state, key string) ([]byte, bool, error) {
	e, err := stdio.State(state).Get(key)
	if err != nil || e == nil {
		return nil, false, err
	}
	return e.Value, true, nil
}

// Keys are a state's keys.
func (States) Keys(state string) ([]string, error) { return stdio.State(state).Keys() }

// Reader is frombus's Reader over this bundle's read states, fetching archives over HTTP.
func Reader() frombus.Reader { return frombus.StatesReader(States{}, HTTPFetch) }

// HTTPFetch reads an archive over HTTP, at most 256 MiB.
func HTTPFetch(ctx context.Context, url string) ([]byte, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("%s answered %s", url, resp.Status)
	}
	return io.ReadAll(io.LimitReader(resp.Body, 256<<20))
}