var metalsmith          = require('metalsmith')
var layouts             = require('metalsmith-layouts')
var markdown            = require('metalsmith-markdown')
var collections         = require('metalsmith-collections')
var pagination          = require('metalsmith-pagination')
var paths               = require('metalsmith-paths')
var filemetadata        = require('metalsmith-filemetadata')
var matters             = require('metalsmith-matters')
var postcss             = require('metalsmith-postcss')

var fs                  = require('fs');
var moment              = require('moment');
var _                   = require('underscore');

var handlebars          = require('handlebars');
var handlebars_layout   = require('handlebars-layouts');

moment.locale('fr');

//--------------------------- Handlebars -----------------------------//
handlebars.registerHelper(handlebars_layout(handlebars));

handlebars.registerHelper('formatDate', function(date) {
    return moment(new Date(date)).format('DD MMMM YYYY');
});

handlebars.registerHelper('formatTimestamp', function(date) {
    return moment(date, 'X').format('MMMM D, YYYY HH:mm:ss');
});

function compareWith(v1, v2, operator) {
    var itm = false;
    
    switch (operator) {
        case '==':
            itm = (v1 == v2);
            break;
        case '!=':
            itm = (v1 != v2);
            break;
        case '===':
            itm = (v1 === v2);
            break;
        case '<':
            itm = (v1 < v2);
            break;
        case '<=':
            itm = (v1 <= v2);
            break;
        case '>':
            itm = (v1 > v2);
            break;
        case '>=':
            itm = (v1 >= v2);
            break;
    }
    return itm;
}

handlebars.registerHelper('eachSorted', function(context, member, item, order, options) {
    var tot = '';

    var entries = _.sortBy(context, function(item){
        return item[member][item] === undefined? 0 : item[member][item];
    })
    
    if (order === 'desc') {
        entries = entries.reverse();
    }

    for (var i = 0; i < entries.length; i++) {
        tot += options.fn(entries[i]);
    }

    return tot;
});

handlebars.registerHelper('eachCenter', function(context, number, index, options) {
    if (number > context.length) {
        number = context.length;
    }
    
    var start = index - number / 2;
    if (start < 0) {
        start = 0;
    }
    
    var end = start + number;
    if (end > context.length) {
        end = context.length;
        start = end - number;
    }
    
    var tot = '';
    
    for (var i = start; i < end; i++) {
        if (i === index) {
            tot += options.inverse(context[i]);
        } else {
            tot += options.fn(context[i]);
        }
    }
    
    return tot;
});

handlebars.registerHelper('ifCond', function (v1, operator, v2, options) {
    if (compareWith(v1, v2, operator)) {
        return options.fn(this);
    } else {
        return options.inverse(this);
    }
});

//--------------------------- Build pipeline -------------------------//
metalsmith(__dirname)
  .source('recettes')
  .metadata(require('./config/metadata'))
  .frontmatter(false)
  .use(matters(require('./config/matters')))
  .use(filemetadata(require('./config/filemetadata')))
  .use(addCategory())
  .use(createCategories())
  .use(collections(require('./config/collections')))
  .use(markdown(require('./config/markdown')))
  .use(pagination(require('./config/pagination')))
  .use(paths(require('./config/paths')))
  .use(layouts(require('./config/layouts')))
  .use(copyVendor())
  .use(postcss(require('./config/postcss')))
  .use(epubGen())
  .destination('build')
  .build(function (err) {
    if (err) {
      throw err
    }
  })


//--------------------- Helper functions -----------------------------//

// Generates an epub file from the list of recettes.
function epubGen() {
    var fs = require('fs');
    var epubGenerator = require('epub-generator');

    return function(files, metalsmith, done) {
        var epubStream = epubGenerator({
            title: metalsmith.metadata().site.title,
            author: metalsmith.metadata().site.authors,
            language: metalsmith.metadata().site.language
        });
        
        for (var f in files) {
            if (files[f].type == 'recette') {
                epubStream.add(f, files[f].contents, {
                    title: files[f].data.title,
                    toc: true
                });
            } else if (files[f].type == 'style') {
                epubStream.add(f, files[f].contents, {
                    toc: false
                });
            }
        }
            
        epubStream.end()
            .pipe( fs.createWriteStream('basic.epub') )
            .on('error', function(err){
                console.trace(err);
            });
        
        return done();
    }
}

function createCategories() {
    return function(files, metalsmith, done) {
        var tagList = {};
        for (var fileName in files) {
            var data = files[fileName];
            if (!data) {
                continue;
            }
            
            var tagsData = data.category;
            if (!tagsData) {
              continue;
            }
            
            if (typeof tagsData === 'string') {
                tagsData = tagsData.split(',');
            }
            
            data.category = [];
            
            tagsData.forEach(function(rawTag) {
                var tag = String(rawTag).trim();
                
                data.category.push(tag);
            
                if (!tagList[tag]) {
                    tagList[tag] = [];
                }
                tagList[tag].push(fileName);
            });
        }
        
        var metadata = metalsmith.metadata();
        metadata.tags = metadata.tags || {};
        
        for (var tag in tagList) {
            var posts = tagList[tag].map(function(fileName) {
                return files[fileName];
            });
            
            var tagPage = files[tag + '/index.md'];
            
            tagPage.tag = tag;
            tagPage.posts = posts;
            tagPage.title = tagPage.data.title;
            
            posts.forEach(function(post) {
                post.categoryPage = tagPage;
            });
            
            metadata['tags'][tag] = tagPage;
        }

        tagList = {};
        
        return done();
    }
}

// Adds the category to the recette entry based on the parent directory
function addCategory() {
    return function(files, metalsmith, done) {
        for (var f in files) {
            if (f.indexOf('.md') > 0 && f.indexOf('index.md') < 0) {
                var idx = f.indexOf('/');
                var cat = f.substring(0, idx);
                
                files[f].category = cat;
                files[f].title = files[f].data.title;
            }
        }
        return done();
    }
}

function copyVendor() {
  return function(files, metalsmith, done){
    var styleFiles = fs.readdirSync('styles');
    for (var i = 0; i < styleFiles.length; i++) {
        var stylePath = 'styles/' + styleFiles[i];
        files[stylePath] = {
            contents: fs.readFileSync(stylePath),
            type: 'style'
        };
    }
    
    var fontFiles = fs.readdirSync('fonts');
    for (var i = 0; i < fontFiles.length; i++) {
        var fontPath = 'fonts/' + fontFiles[i];
        files[fontPath] = {
            contents: fs.readFileSync(fontPath),
            type: 'font'
        };
    }
    
    return done();
  };
}