'use strict';


var common        = require('./common');
var YAMLException = require('./exception');
var Type          = require('./type');


function compileList(schema, name, result) {
  var exclude = [];

  schema.include.forEach(function (includedSchema) {
    result = compileList(includedSchema, name, result);
  });

  schema[name].forEach(function (currentType) {
    result.forEach(function (previousType, previousIndex) {
      if (previousType.tag === currentType.tag) {
        exclude.push(previousIndex);
      }
    });

    result.push(currentType);
  });

  return result.filter(function (type, index) {
    return -1 === exclude.indexOf(index);
  });
}


function compileMap(/* lists... */) {
  var result = {}, index, length;

  function collectType(type) {
    result[type.tag] = type;
  }

  for (index = 0, length = arguments.length; index < length; index += 1) {
    arguments[index].forEach(collectType);
  }

  return result;
}


function Schema(definition) {
  this.include  = definition.include  || [];
  this.implicit = definition.implicit || [];
  this.explicit = definition.explicit || [];

  this.implicit.forEach(function (type) {
    if (null !== type.loader && 'string' !== type.loader.kind) {
      throw new YAMLException('There is a non-scalar type in the implicit list of a schema. Implicit resolving of such types is not supported.');
    }
  });

  this.compiledImplicit = compileList(this, 'implicit', []);
  this.compiledExplicit = compileList(this, 'explicit', []);
  this.compiledTypeMap  = compileMap(this.compiledImplicit, this.compiledExplicit);
}


Schema.DEFAULT = null;


Schema.create = function createSchema() {
  var schemas, types;

  switch (arguments.length) {
  case 1:
    schemas = Schema.DEFAULT;
    types = arguments[0];
    break;

  case 2:
    schemas = arguments[0];
    types = arguments[1];
    break;

  default:
    throw new YAMLException('Wrong number of arguments for Schema.create function');
  }

  schemas = common.toArray(schemas);
  types = common.toArray(types);

  if (!schemas.every(function (schema) { return schema instanceof Schema; })) {
    throw new YAMLException('Specified list of super schemas (or a single Schema object) contains a non-Schema object.');
  }

  if (!types.every(function (type) { return type instanceof Type; })) {
    throw new YAMLException('Specified list of YAML types (or a single Type object) contains a non-Type object.');
  }

  return new Schema({
    include: schemas,
    explicit: types
  });
};


module.exports = Schema;
