package workflow

import (
	"errors"
	"io"
	"io/fs"
	"os"
	"path/filepath"

	lop "github.com/samber/lo/parallel"
	"gopkg.in/yaml.v3"
)

type WorkflowFiles []io.Reader

func (wo WorkflowFiles) Close() error {
	var errs []error
	for _, reader := range wo {
		if reader, ok := reader.(io.ReadCloser); ok {
			errs = append(errs, reader.Close())
		}
	}
	return errors.Join(errs...)
}

func (wo WorkflowFiles) Workflows() ([]Workflow, error) {
	var (
		errs      = []error{}
		workflows = make([]Workflow, 0, len(wo))
	)

	lop.ForEach(wo, func(reader io.Reader, _ int) {
		var w Workflow
		if err := yaml.NewDecoder(reader).Decode(&w); err != nil {
			errs = append(errs, err)
		} else {
			workflows = append(workflows, w)
		}
		if rc, ok := reader.(io.ReadCloser); ok {
			if err := rc.Close(); err != nil {
				errs = append(errs, err)
			}
		}
	})

	return workflows, errors.Join(errs...)
}

type DirFilter = func(path string, d fs.FileInfo) bool

// OpenDir opens a directory and returns a WorkflowInput.
//
// Set filter to filter out unwanted files.
func OpenDir(dir string, filters ...DirFilter) (WorkflowFiles, error) {
	var files []io.Reader
	err := filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		ok := true
		for _, filter := range filters {
			ok = filter(path, info)
			if !ok {
				break
			}
		}
		if ok {
			file, err := os.Open(path)
			if err != nil {
				return err
			}
			files = append(files, file)
		}
		return nil
	})
	if err != nil {
		return nil, err
	}

	return WorkflowFiles(files), nil
}

// WorkflowFromReaders creates a WorkflowInput from a list of io.Reader.
//
// If the Reader implements io.ReadCloser, it will be used as is.
// If not, it will be wrapped with io.NopCloser.
//
// WorkflowFromReaders assumes ownership of the Readers and will close (if implements io.ReadCloser)
// all of them after the WorkflowInput is consumed (whether successfully or not).
func WorkflowFromReaders(readers ...io.Reader) WorkflowFiles {
	return WorkflowFiles(readers)
}