package user

import (
	"errors"
	"fmt"
	"os"
	"strings"

	"gopkg.in/yaml.v3"
)

// ErrRequiredField is wrapped by validation errors so callers can detect an
// owner profile that is missing required fields.
var ErrRequiredField = errors.New("user: required field missing")

// LoadOwnerProfile reads and validates the owner profile YAML at path.
func LoadOwnerProfile(path string) (*OwnerProfile, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("user: read %s: %w", path, err)
	}
	p := &OwnerProfile{}
	if err := yaml.Unmarshal(data, p); err != nil {
		return nil, fmt.Errorf("user: parse %s: %w", path, err)
	}
	if err := p.validate(); err != nil {
		return nil, err
	}
	return p, nil
}

// validate checks the owner profile for its required fields and for partial
// whitelist entries. An empty whitelist is allowed: on a fresh install nobody
// has been configured as owner, so the policy engine defaults to deny until the
// operator fills in account ids (fail-safe, per design/11).
func (p *OwnerProfile) validate() error {
	var missing []string
	if strings.TrimSpace(p.ID) == "" {
		missing = append(missing, "id")
	}
	if strings.TrimSpace(p.DisplayName) == "" {
		missing = append(missing, "displayName")
	}
	if len(missing) > 0 {
		return fmt.Errorf("%w: missing %s", ErrRequiredField, strings.Join(missing, ", "))
	}
	for i, a := range p.Accounts {
		pe := strings.TrimSpace(a.Platform) == ""
		ae := strings.TrimSpace(a.AccountID) == ""
		switch {
		case pe && ae:
			// Fully-empty entry: an unconfigured placeholder, skip it.
			continue
		case pe || ae:
			return fmt.Errorf("%w: accounts[%d] requires both platform and accountId", ErrRequiredField, i)
		}
	}
	return nil
}