package convids

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	fp "path/filepath"
	"regexp"
	"strings"

	"gopkg.in/yaml.v3"
)

func NewData(path string) (*Data, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	ydec := yaml.NewDecoder(f)
	var data Data
	err = ydec.Decode(&data)
	return &data, err
}

func ensureExtRe(c *Config) (err error) {
	if c.extRe != nil {
		return nil
	}
	c.extRe, err = regexp.Compile("(" + strings.Join(c.Extensions, "|") + ")$")
	return
}

type ShowWalker func(show *Show, path string) error
type GroupPrinter func(name string, group Shows)

var ErrNoFiles = errors.New("no files processed")
var ErrSkipped = errors.New("skipped")

func processFile(conf *Config, walk ShowWalker, show *Show, file os.DirEntry) (processed bool, processError, cbError error) {
	if file.IsDir() {
		return
	}
	if !conf.extRe.MatchString(file.Name()) {
		return
	}
	var found bool
	found, processError = show.Match(file.Name())
	if processError != nil || !found {
		return
	}

	path := fp.Join(conf.Source, file.Name())
	for _, ext := range conf.Skip {
		if !strings.HasPrefix(ext, ".") {
			ext = "." + ext
		}
		skipper := path + ext
		_, statErr := os.Stat(skipper)
		if !errors.Is(statErr, os.ErrNotExist) {
			return processed, ErrSkipped, cbError
		}
	}

	cbError = walk(show, path)
	if cbError == nil {
		processed = true
	}
	return
}

func WalkFiles(d *Data, stopOnError bool, gp GroupPrinter, cb ShowWalker) (err error) {
	err = ensureExtRe(d.Config)
	if err != nil {
		return
	}
	if cb == nil {
		cb = DryRun(os.Stdout)
	}
	count := 0
	var files []os.DirEntry
	files, err = os.ReadDir(d.Config.Source)
	if err != nil {
		return
	}
	for s := range d.AllShows(gp) {
		for _, file := range files {
			processed, processErr, cbErr := processFile(d.Config, cb, s, file)
			if !processed && processErr == nil && cbErr == nil {
				continue
			}
			if errors.Is(processErr, ErrSkipped) {
				continue
			}
			if processErr != nil {
				return processErr
			}
			if cbErr != nil && stopOnError {
				return cbErr
			}
			if cbErr == nil && processed {
				count++
			}
			if cbErr != nil {
				err = cbErr
			}
			break
		}
	}
	if err == nil && count < 1 {
		fmt.Println("Found nothing")
		return ErrNoFiles
	}
	return
}

func DryRun(out io.Writer) ShowWalker {
	return func(s *Show, path string) error {
		fmt.Fprintf(out, "Saving %s to %s\n", path, s.Folder)
		return ErrSkipped
	}
}

func GetShow(ctx context.Context) ShowWalker {
	return func(s *Show, path string) error {
		cmd := exec.CommandContext(ctx, "get-shows", s.Folder, path)
		cmd.Stdin = os.Stdin
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		return cmd.Run()
	}
}

func PrintGroupName(out io.Writer) GroupPrinter {
	return func(name string, group Shows) {
		fmt.Fprintf(out, "Checking %s shows\n\n", name)
	}
}