package ignore

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"slices"
	"strings"

	ignore "github.com/sabhiram/go-gitignore"

	"alin.ovh/erl/repository"
)

var DefaultIgnoreFilename = ".ignore"

type Filter struct {
	repo        *repository.Repo
	projectRoot string
	wd          string

	givenPaths []string
	paths      []string
	ignores    []*Ignore
}

type Ignore struct {
	*ignore.GitIgnore

	filename string
}

func New(wd string, path ...string) *Filter {
	return &Filter{
		wd:         wd,
		givenPaths: path,
	}
}

func (f *Filter) ReadIgnoreFiles(ctx context.Context) error {
	if f.projectRoot == "" {
		repo, err := repository.GetRepo(ctx, f.wd)
		if err != nil {
			return err
		}

		f.repo = repo
		f.projectRoot = repo.GetRoot()
	}

	err := f.getPaths()
	if err != nil {
		return err
	}

	f.ignores = []*Ignore{}
	for _, path := range f.paths {
		ig, err := ignore.CompileIgnoreFile(path)
		if err != nil {
			return err
		}

		f.ignores = append(f.ignores, &Ignore{
			GitIgnore: ig,
			filename:  path,
		})
	}

	return nil
}

func (f *Filter) Ignored(path string) bool {
	return slices.ContainsFunc(f.ignores, func(ig *Ignore) bool {
		return ig.MatchesPath(path)
	})
}

func (f *Filter) getPaths() error {
	f.paths = f.givenPaths

	rel, err := filepath.Rel(f.projectRoot, f.wd)
	if err != nil {
		return err
	}

	ignoreFileNames := []string{DefaultIgnoreFilename}
	ignoreFileNames = append(ignoreFileNames, f.repo.GetIgnoreFileNames()...)
	dirs := strings.Split(rel, string(filepath.Separator))
	for i := range dirs {
		var dir string
		if i == 0 {
			dir = "."
		} else {
			dir = filepath.Join(dirs[:i+1]...)
		}

		for _, basename := range ignoreFileNames {
			filename := filepath.Join(f.projectRoot, dir, basename)
			stat, err := os.Stat(filename)
			if err != nil {
				if errors.Is(err, os.ErrNotExist) {
					continue
				}

				return err
			}
			if stat.IsDir() {
				return fmt.Errorf(
					"%s path is a directory: %s",
					basename,
					filepath.Join(f.projectRoot, dir, filename),
				)
			}

			f.paths = append(f.paths, filename)
		}
	}

	return nil
}