package host

import (
	"bytes"
	"encoding/json"
	"io"
	"os"

	"github.com/carlosframework/platform/internal/rootstate"
)

func readClaimUnitShapes(path string) (map[string]claimUnitShape, error) {
	f, err := rootstate.OpenAuthorityFile(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	raw, err := io.ReadAll(io.LimitReader(f, rootstate.MaxRecord+1))
	if err != nil {
		return nil, err
	}
	return decodeClaimUnitShapes(raw)
}

func decodeClaimUnitShapes(raw []byte) (map[string]claimUnitShape, error) {
	var config struct {
		Schema int
		Units  []claimUnitShape
	}
	dec := json.NewDecoder(bytes.NewReader(raw))
	dec.DisallowUnknownFields()
	if len(raw) > rootstate.MaxRecord || dec.Decode(&config) != nil || dec.Decode(new(any)) != io.EOF || config.Schema != 1 || len(config.Units) > 4096 {
		return nil, os.ErrPermission
	}
	hosts, units := map[string]claimUnitShape{}, map[string]bool{}
	for _, s := range config.Units {
		if !s.valid() || hosts[s.Host].Host != "" || units[s.Unit] {
			return nil, os.ErrPermission
		}
		hosts[s.Host], units[s.Unit] = s, true
	}
	return hosts, nil
}