// Copyright © 2016 Jip J. Dekker <jip@dekker.li>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package settings

import (
	"bufio"
	"encoding/json"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"

	log "github.com/Sirupsen/logrus"
	"github.com/jjdekker/ponder/helpers"
)

const lyToken = "% PONDER"

// Score represents the settings for a specific score file
type Score struct {
	Name         string    // The name of the score in the songbook
	Categories   []string  `json:",omitempty"` // Categories to which the scores belong
	Path         string    // The path to the scores (uncompiled) file
	LastModified time.Time `json:"-"`          // Time when the score source was last modified (will be set internally)
	OutputPath   string    `json:",omitempty"` // The path on which the compiled version of the score will be placed
}

// FromJSON reads the settings of a score from a JSON file
func FromJSON(path string) (*Score, error) {
	data, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, err
	}

	var s Score
	err = json.Unmarshal(data, &s)
	if err != nil {
		return nil, err
	}
	s.LastModified = helpers.LastModified(s.Path)

	return &s, nil
}

// FromLy reads the score metadata from a lilypond file.
// The metadata should be on one line preceded by the lyToken.
// The data itself should be in json format.
func FromLy(path string) (*Score, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	scan := bufio.NewScanner(file)
	var line string
	for scan.Scan() {
		if strings.Contains(scan.Text(), lyToken) {
			line = strings.TrimLeftFunc(scan.Text(), func(r rune) bool {
				return r != '{'
			})
			break
		}
	}
	file.Close()

	var s Score
	if line != "" {
		err = json.Unmarshal([]byte(line), &s)
		if err != nil {
			return nil, err
		}
	}
	if s.Name == "" {
		s.Name = filepath.Base(path)[:strings.LastIndex(filepath.Base(path), ".")]
	}
	s.Path = path

	return &s, nil
}

// CreateScore creates a json file for a score given its path
func CreateScore(path, workDir string) {
	if filepath.Ext(path) != ".pdf" {
		log.WithFields(log.Fields{"path": path}).
			Warning("Unsupported sheet music file")
	}

	jsonPath := path[:strings.LastIndex(path, ".")]
	s := Score{
		Path: path,
		Name: filepath.Base(jsonPath),
	}

	if filepath.Dir(path) != workDir {
		s.Categories = []string{filepath.Base(filepath.Dir(path))}
	}

	data, err := json.MarshalIndent(s, "", "  ")
	helpers.Check(err, "Unable to generate valid json")
	err = ioutil.WriteFile(jsonPath+".json", data, 0644)
	helpers.Check(err, "Unable to save json to file")
}

// GenerateOutputPath fills path that the compiled score will take
func (s *Score) GenerateOutputPath(opts *Settings) {
	if s.OutputPath != "" {
		return
	}
	file := filepath.Base(s.Path)
	dot := strings.LastIndex(file, ".")
	if dot == -1 {
		log.WithFields(log.Fields{"path": s.Path}).Error("Unable to compute output path")
		return
	}
	file = file[:dot+1] + "pdf"
	s.OutputPath = filepath.Join(opts.OutputDir, file)
}

// Scores aliases a slice of scores
type Scores []Score

// ScoresByName implements sort.Interface by providing Less and using the Len and
// Swap methods of the embedded Scores value.
type ScoresByName struct{ Scores }

// Len returns the number of scores and
// implements part of the sort.Interface
func (s Scores) Len() int { return len(s) }

// Swap interchanges the position of two scores and
// implements part of the sort.Interface
func (s Scores) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

// Less reports whether the name of the score on position i is
// smaller than the name of the score on position j
// and implements part of the sort.Interface
func (s ScoresByName) Less(i, j int) bool {
	return s.Scores[i].Name < s.Scores[j].Name
}