Implement simple article queriing utility

Example usage:

node query.js --sql "select metadata.tags as tags, metadata.title as title where count(metadata.tags) == 1 and contains(metadata.tags, 'Článek');"

prints list of articles which have only tag "Článek" - usefull for
listing not yet tagged articles

package.json

@@ -23,6 +23,7 @@
     "nodegit": "^0.11.7",
     "nunjucks": "^2.3.0",
     "nunjucks-date-filter": "^0.1.1",
+    "sqlite-parser": "^0.14.3",
     "syntax-error": "^1.1.5",
     "toml": "^2.3.0",
     "toml-js": "0.0.8",

query.js

+var sqliteParser = require('sqlite-parser');
+var cli = require('cli');
+var options = cli.parse({
+ contentdir: [null, 'Allows to specify arbitrary content directory.', 'string', 'content'],
+ sql: ['q', 'SQL querry', 'string']
+});
+
+var ast = sqliteParser(options.sql).statement[0];
+
+console.log(JSON.stringify(ast,null,'  '));
+
+var getProp = function(prop, article) {
+  var ret = article;
+  prop.split('.').forEach(function(p) {
+    if(ret === undefined) return;
+    ret = ret[p];
+  });
+  return ret;
+}
+
+var functions = {
+  'contains': function(context, args) {
+    if(args.length !== 2) throw new Error('Wrong number of arguments for function contains');
+    var prop = evalExpr(context, args[0]);
+    if(!Array.isArray(prop)) return false;
+    var val = evalExpr(context, args[1]);
+    var ret = false;
+    prop.forEach(function(el) {
+      if(el == val) ret = true;
+    })
+    return ret;
+  },
+  'count': function(context, args) {
+    if(args.length !== 1) throw new Error('Wrong number of arguments for function count');
+    var prop = evalExpr(context, args[0]);
+    if(prop === undefined) return 0;
+    if(!Array.isArray(prop)) return 1;
+    return prop.length;
+  }
+}
+
+var binaryOperators = {
+  'and': function(context, left, right) {
+    return evalExpr(context, left) && evalExpr(context, right);
+  },
+  'or': function(context, left, right) {
+    return evalExpr(context, left) || evalExpr(context, right);
+  },
+  '==': function(context, left, right) {
+    return evalExpr(context, left) == evalExpr(context, right);
+  },
+  '>': function(context, left, right) {
+    return evalExpr(context, left) > evalExpr(context, right);
+  },
+  '<': function(context, left, right) {
+    return evalExpr(context, left) < evalExpr(context, right);
+  },
+  '>=': function(context, left, right) {
+    return evalExpr(context, left) >= evalExpr(context, right);
+  },
+  '<=': function(context, left, right) {
+    return evalExpr(context, left) <= evalExpr(context, right);
+  },
+  '!=': function(context, left, right) {
+    return evalExpr(context, left) != evalExpr(context, right);
+  },
+}
+
+var literals = {
+  'decimal': function(context, value) {
+    return Number(value);
+  },
+  'string': function(context, value) {
+    return value;
+  }
+}
+
+var evalExpr = function(context, expr) {
+  if(expr.type == 'identifier') {
+    return getProp(expr.name, context);
+  } else if(expr.type == 'expression' && expr.format == 'binary') {
+    if(typeof binaryOperators[expr.operation] === 'function') {
+      return binaryOperators[expr.operation](context, expr.left, expr.right);
+    } else {
+      throw new Error('Unsupported binary operator '+expr.operation);
+    }
+  } else if(expr.type == 'function') {
+    if(typeof functions[expr.name] === 'function') {
+      return functions[expr.name](context, expr.args);
+    } else {
+      throw new Error('Unsupported function '+expr.name);
+    }
+  } else if(expr.type == 'literal') {
+    if(typeof literals[expr.variant] === 'function') {
+      return literals[expr.variant](context, expr.value);
+    } else {
+      throw new Error('Unsupported literal variant '+expr.variant);
+    }
+  } else {
+    throw new Error('Unsupported expression '+JSON.stringify(expr));
+  }
+  throw new Error('Code should not get here. This is really bad.');
+}
+
+var jobs = require('./sitegin/jobs');
+jobs.registerMultiple(
+  {},
+  ['parseHugo', './parseHugo'],
+  ['readFiles', './readFiles']
+)
+.then(function() {
+  return jobs.run('readFiles',{config:{
+    sourceDir: options.contentdir,
+    articlesLocation: 'articles',
+    redirectsLocation: 'redirects'
+  }})
+})
+.then(function(obj) {
+  return jobs.run('parseHugo',obj)
+})
+.then(function(obj){
+  return obj.pages
+})
+.then(function(pages) {
+  return pages.filter(function(page) {
+    return evalExpr(page, ast.where[0]);
+  })
+})
+.then(function(pages) {
+  var results = ast.result;
+  if(results[0].variant == 'star') {
+    pages.forEach(function(page) {
+      console.log(JSON.stringify(page));
+    })
+    return;
+  }
+  pages.forEach(function(page) {
+    var n = {};
+    results.forEach(function(result) {
+      if(result.alias) n[result.alias] = getProp(result.name, page);
+      else n[result.name] = getProp(page, result.name);
+    })
+    console.log(n);
+  })
+})
+.then(function() {
+  process.exit(0);
+})
+.catch(function(e) {
+  console.log(e.stack);
+  process.exit(1);
+})

sitegin/config.js

+'use strict';
 /*
  * This file specifies whole configuration of sitegin.
- * In future it might actually read configuration files but for now - if you
- * want to configure sitegin you have to modify this file.
- * (or write config reader which would replace this file - I'd appreciate
- * merge request for this feature ;) )
+ * It reads config file from content/config.toml it also parses command-line
+ * arguments. CLI args take precedence over config options
  */
 var Git = require('nodegit');
 var cli = require('cli');
+var fs = require('fs');
+var path = require('path');
+var toml = require('toml');
 var options = cli.parse({
  noserver: ['n', 'Dont run server'],
  port: ['p', 'Port on which server should run', 'number', 1337],
@@ -30,20 +32,25 @@ module.exports = function() {
     options.uiport = options.port+1;
   }
 
-  return new Promise(function(resolve, reject){
-    function doResolve() {
-      resolve({config: {
-        options: options,
-        builddir: builddir,
-        sourceDir: options.contentdir,
-        staticDir: options.staticdir,
-        themeDir: options.themedir,
-        articlesLocation: 'articles',
-        redirectsLocation: 'redirects',
-        linksPerPage: 6
-      }});
-    }
-    doResolve();
+  return new Promise(function(resolve, reject) {
+    var config = {
+      options: options,
+      builddir: builddir,
+      sourceDir: options.contentdir,
+      staticDir: options.staticdir,
+      themeDir: options.themedir,
+      articlesLocation: 'articles',
+      redirectsLocation: 'redirects',
+      linksPerPage: 6
+    };
+    var configFile = path.join(config.sourceDir, 'config.toml');
+    fs.readFile(configFile,'utf-8',function(err,data) {
+      if(err) return reject('Error reading '+configFile);
+      data = toml.parse(data);
+      console.log(data);
+      for(let attr in config) { data[attr] = config[attr]; }
+      resolve({config: data});
+    })
   })
 }
 module.exports.watch = !options.noserver;