package accessctl

import (
	"errors"
	"fmt"

	"github.com/bmatcuk/doublestar"
)

// StringMatcher is used to match against a string. It can use one of several
// methods to match. Only one field should be filled at a time.
type StringMatcher struct {
	// Pattern, if set, indicates that the Match method should succeed if this
	// doublestar pattern matches against the string.
	Pattern string `yaml:"pattern,omitempty"`

	// Patterns, if set, indicates that the Match method should succeed if at
	// least one of these doublestar patterns matches against the string.
	Patterns []string `yaml:"patterns,omitempty"`
}

func doublestarMatch(pattern, str string) (bool, error) {
	ok, err := doublestar.Match(pattern, str)
	if err != nil {
		return false, fmt.Errorf("matching %q on pattern %q: %w",
			str, pattern, err)
	}
	return ok, nil
}

// Match operates similarly to the Match method of the FilterInterface, except
// it only takes in strings.
func (m StringMatcher) Match(str string) error {
	switch {
	case m.Pattern != "":
		if ok, err := doublestarMatch(m.Pattern, str); err != nil {
			return err
		} else if !ok {
			return ErrFilterNoMatch{
				Err: fmt.Errorf("pattern %q does not match %q", m.Pattern, str),
			}
		}
		return nil

	case len(m.Patterns) > 0:
		for _, pattern := range m.Patterns {
			if ok, err := doublestarMatch(pattern, str); err != nil {
				return err
			} else if ok {
				return nil
			}
		}
		return ErrFilterNoMatch{
			Err: fmt.Errorf("no patterns in %+v match %q", m.Patterns, str),
		}

	default:
		return errors.New(`one of the following fields must be set: "pattern", "patterns"`)
	}
}

// FilterBranch matches a CommitRequest's Branch field using a double-star
// pattern.
type FilterBranch struct {
	StringMatcher StringMatcher `yaml:",inline"`
}

var _ Filter = FilterBranch{}

// MatchCommit implements the method for FilterInterface.
func (f FilterBranch) MatchCommit(req CommitRequest) error {
	return f.StringMatcher.Match(req.Branch)
}

// FilterFilesChanged matches a CommitRequest's FilesChanged field using a
// double-star pattern. It only matches if all of the CommitRequest's
// FilesChanged match.
type FilterFilesChanged struct {
	StringMatcher StringMatcher `yaml:",inline"`
}

var _ Filter = FilterFilesChanged{}

// MatchCommit implements the method for FilterInterface.
func (f FilterFilesChanged) MatchCommit(req CommitRequest) error {
	for _, path := range req.FilesChanged {
		if err := f.StringMatcher.Match(path); errors.As(err, new(ErrFilterNoMatch)) {
			continue
		} else if err != nil {
			return err
		}
		return nil
	}

	return ErrFilterNoMatch{Err: errors.New("no paths matched")}
}