'use strict';

function lowerFirst(str) {
  return str.charAt(0).toLowerCase() + str.substr(1);
}
function snakeCase(str) {
  return lowerFirst(str).replace(/([A-Z])/g, function (match) {
    return "_" + match.toLowerCase();
  });
}
function camelCase(str) {
  return str.replace(/_([a-z])/g, function (match) {
    return match[1].toUpperCase();
  });
}
function upperCamelCase(str) {
  var camel = camelCase(str);
  return camel.charAt(0).toUpperCase() + camel.substr(1);
}

var searchConditions = {
  '=':  true,
  '==': true,
  '!=': true,
  '<>': true,
  '<':  true,
  '<=': true,
  '!<': true,
  '>':  true,
  '>=': true,
  '!>': true,
  'IS': true,
  'IS NOT': true,

  'IN':          true,
  'NOT IN':      true,
  'LIKE':        true,
  'NOT LIKE':    true,
  'GLOB':        true,
  'NOT GLOB':    true,
  'BETWEEN':     true,
  'NOT BETWEEN': true,
};

function wrap(db, dir, dbsMap) {
  // TODO if I put a failure right here,
  // why doesn't the unhandled promise rejection fire?
  var PromiseA = require('bluebird');
  var promises = [];
  var earr = [];
  var debug = false;

  if (!dbsMap) {
    dbsMap = {};
  }

  // PRAGMA schema.table_info(table-name);
  //
  function sqlite3GetColumns(tablename, columns, cb) {
    var sql = "PRAGMA table_info(" + db.escape(tablename) + ")";

    db.all(sql, earr, function (err, result) {
      if (err) {
        console.error('[Error] query columns');
        console.error(err.stack);
        cb(err);
        return;
      }

      if (debug) {
        console.log('sqlite3 rows 0');
        console.log(result);
      }

      function alterTable() {
        var column = columns.pop();
        var sql;

        if (!column) {
          cb(null);
          return;
        }

        if ((result.rows||result).some(function (row) {
          return (row.column_name || row.name) === snakeCase(column.name);
        })) {
          alterTable();
          return;
        }

        sql = "ALTER TABLE " + db.escape(tablename)
          + " ADD COLUMN "
          + db.escape(column.name) + " " + db.escape(column.type)
          + " DEFAULT null"
          ;

        if (debug) {
          console.log('sqlite3 1');
          console.log(sql);
        }

        db.all(sql, earr, function (err, results) {
          if (err) {
            console.error("[Error] add column '" + tablename + "'");
            console.error(sql);
            console.error(err.stack || new Error('stack').stack);
            cb(err);
            return;
          }

          if (debug) {
            console.log('sqlite3 rows 1');
            console.log(results);
          }

          alterTable();
        });
      }

      columns = columns.slice(0);
      alterTable();
    });
  }

  function normalizeColumn(col, i, arr) {
    if ('string' === typeof col) {
      col = arr[i] = { name: col, type: 'text' };
    }

    if (!col.type) {
      col.type = 'text';
    }

    col.type = col.type.toLowerCase(); // oh postgres...
    col.name = snakeCase(col.name);

    return col;
  }

  function createTable(dir) {
    if (!dir.modelname && !dir.tablename) {
      throw new Error('Please specify dir.modelname');
    }

    if (!dir.tablename) {
      dir.tablename = snakeCase(dir.modelname);
    }

    if (!dir.modelname) {
      dir.modelname = upperCamelCase(dir.tablename);
    }

    if (!dir.indices) {
      dir.indices = [];
    }

    var DB = {};
    var tablename = (db.escape(dir.tablename || 'data'));
    var idname = (db.escape(dir.idname || 'id'));
    var idnameCased = (camelCase(dir.idname || 'id'));

    dir.indices.forEach(normalizeColumn);
    DB._indices = dir.indices;
    DB._indicesMap = {};
    DB._indices.forEach(function (col) {
      DB._indicesMap[col.name] = col;
    });

    function simpleMap(rows) {
      if (!rows) {
        return [];
      }

      var results = rows.map(function (row, i) {
        // set up for garbage collection
        rows[i] = null;

        var obj;

        if (row.json) {
          obj = JSON.parse(row.json);
        } else {
          obj = {};
        }
        delete row.json;

        obj[idnameCased] = row[idname];
        delete row[idname];

        Object.keys(row).forEach(function (fieldname) {
          // Ideally it shouldn't be possible to overriding a former proper column,
          // but when a new indexable field is added, the old value is still in json
          // TODO one-time upgrade of all rows when a new column is added
          if (null === row[fieldname] || 'undefined' === typeof row[fieldname] || '' === row[fieldname]) {
            obj[camelCase(fieldname)] = row[fieldname] || obj[camelCase(fieldname)] || row[fieldname];
          }
          else {
            obj[camelCase(fieldname)] = row[fieldname];
          }
        });

        return obj;
      });
      // set up for garbage collection
      rows.length = 0;
      rows = null;

      return results;
    }

    function simpleParse(row) {
      if (!row) {
        return null;
      }

      return simpleMap([row])[0] || null;
    }

    // pull indices from object
    function strainUpdate(id, data/*, vals*/, cb, oldId) {
      var fieldable = [];
      var sql;
      var vals = [];

      ['hasOne', 'hasMany', 'hasAndBelongsToMany', 'belongsTo', 'belongsToMany'].forEach(function (relname) {
        var rels = dir[relname];

        if (!rels) {
          return;
        }

        if (!Array.isArray(rels)) {
          rels = [rels];
        }

        // don't save relationships
        rels.forEach(function (colname) {
          delete data[colname];
          delete data[camelCase(colname)];
          // TODO placehold relationships on find / get?
          // data[camelCase(colname)] = null;
        });
      });

      dir.indices.forEach(function (col) {
        // We prioritze the raw name rather than the camelCase name because it's not in the object
        // we give for retrieved entries, so if it's present then the user put it there themselves.
        var val = data[col.name] || data[camelCase(col.name)];

        //if (col.name in data)
        if ('undefined' !== typeof val) {
          /*
          fieldable.push(
            db.escape(snakeCase(col.name))
          + " = '" + db.escape(val) + "'"
          );
          */
          fieldable.push(db.escape(snakeCase(col.name)));
          vals.push(val);
        }

        delete data[col.name];
        delete data[camelCase(col.name)];
      });

      if (!oldId) {
        delete data[idnameCased];
      }

      if (!fieldable.length || Object.keys(data).length) {
        vals.push(JSON.stringify(data));
      } else {
        vals.push(null);
      }
      fieldable.push('json');

      vals.push(id);

      sql = cb(fieldable);

      if (debug) {
        console.log('[masterquest-sqlite3] dbwrap.js');
        console.log(sql);
        console.log(vals);
      }

      vals.forEach(function (val) {
        if (null === val || 'number' === typeof val) {
          sql = sql.replace('?', String(val));
        } else {
          sql = sql.replace('?', "'" + db.escape(val) + "'");
        }
      });

      return sql;
    }

    DB.migrate = function (columns) {
      columns.forEach(normalizeColumn);

      return new PromiseA(function (resolve, reject) {
        sqlite3GetColumns(tablename, columns, function (err) {
          if (err) {
            reject(err);
            return;
          }

          resolve();
        });
      });
    };

    DB.find = function (obj, params) {
      var err;
      var sql = 'SELECT * FROM \'' + tablename + '\' ';
      var keys = obj && Object.keys(obj);

      if (obj) {
        Object.keys(obj).forEach(function (key) {
          if (undefined === obj[key]) {
            err = new Error("'" + key + "' was `undefined'. For security purposes you must explicitly set the value to null or ''");
          }
        });
      }
      if (err) {
        return PromiseA.reject(err);
      }

      if (params && params.limit) {
        params.limit = parseInt(params.limit, 10);
        // remember to check for the case of NaN
        if (!params.limit || params.limit <= 0) {
          return PromiseA.reject(new Error('limit must be a positive integer'));
        }
      }

      if (obj && keys.length) {
        var conditions = keys.map(function (key) {
          var dbKey = db.escape(snakeCase(key));
          var value = obj[key];
          if (null === value) {
            return dbKey + ' IS NULL';
          }

          var split, cmd;
          if (typeof value === 'string') {
            value = value.trim();
            if (['IS NULL', 'IS NOT NULL'].indexOf(value.toUpperCase()) !== -1) {
              return dbKey + ' ' + value.toUpperCase();
            }

            split = value.split(' ');
            if (searchConditions[split[0].toUpperCase()]) {
              cmd = split[0].toUpperCase();
              value = split.slice(1).join(' ');
            } else if (searchConditions[split.slice(0, 2).join(' ').toUpperCase()]) {
              cmd = split.slice(0, 2).join(' ').toUpperCase();
              value = split.slice(2).join(' ');
            }
            // If we were given something like "BEGINS WITH 'something quoted'" we don't want
            // to include the quotes (we'll quote it again later) so we strip them out here.
            if (cmd) {
              value = value.replace(/^(['"])(.*)\1$/, '$2');
            }
          }
          if (typeof value === 'object') {
            cmd = value.condition || value.relation || value.cmd;
            value = value.value;
            if (!cmd || !value) {
              err = new Error("'"+key+"' was an object, but missing condition and/or value");
              return;
            }
            if (typeof cmd !== 'string' || !searchConditions[cmd.toUpperCase()]) {
              err = new Error("'"+key+"' tried to use invalid condition '"+cmd+"'");
              return;
            } else {
              cmd = cmd.toUpperCase();
            }
          }

          if (!cmd) {
            cmd = '=';
          }
          // The IN condition is special in that we can't quote the value as a single value,
          // so it requires a little more logic to actually work and still be sanitary.
          if (cmd === 'IN' || cmd === 'NOT IN') {
            if (typeof value === 'string') {
              value = value.split((params || {}).seperator || /[\s,]+/);
            }
            if (!Array.isArray(value)) {
              err = new Error("'"+key+"' has invalid value for use with 'IN'");
              return;
            }
            value = value.map(function (val) {
              return "'"+db.escape(val)+"'";
            });
            return dbKey + ' ' + cmd + ' (' + value.join(',') + ')';
          }
          // The BETWEEN condition is also special for the same reason as IN
          if (cmd === 'BETWEEN' || cmd === 'NOT BETWEEN') {
            if (typeof value === 'string') {
              value = value.split((params || {}).seperator || /[\s,]+(AND\s+)?/i);
            }
            if (!Array.isArray(value) || value.length !== 2) {
              err = new Error("'"+key+"' has invalid value for use with 'BETWEEN'");
              return;
            }
            value = value.map(function (val) {
              return "'"+db.escape(val)+"'";
            });
            return dbKey + ' ' + cmd + ' ' + value.join(' AND ');
          }
          // If we are supposed to compare to another field then make sure the name is correct,
          // and that we don't try to quote the name.
          if (typeof value === 'string' && /^[a-zA-Z0-9_]*$/.test(value)) {
            var snake = snakeCase(value);
            if (dir.indices.some(function (col) { return snake === col.name; })) {
              return dbKey + ' ' + cmd + ' ' + snake;
            }
          }
          return dbKey + ' ' + cmd + " '" + db.escape(value) + "'";
        });
        if (err) {
          return PromiseA.reject(err);
        }

        sql += 'WHERE ' + conditions.join(' AND ');
      }
      else if (null !== obj || !(params && params.limit)) {
        return PromiseA.reject(new Error("to find all you must explicitly specify find(null, { limit: <<int>> })"));
      }

      if (params) {
        if (typeof params.orderByDesc === 'string' && !params.orderBy) {
          params.orderBy = params.orderByDesc;
          params.orderByDesc = true;
        }

        // IMPORTANT: " is not the same to sqlite as '.
        // // " is exact and necessary
        if (params.orderBy) {
          sql += " ORDER BY \"" + db.escape(snakeCase(params.orderBy)) + "\" ";
          if (params.orderByDesc) {
            sql += "DESC ";
          }
        } else if (DB._indicesMap.updated_at) {
          sql += " ORDER BY \"updated_at\" DESC ";
        } else if (DB._indicesMap.created_at) {
          sql += " ORDER BY \"created_at\" DESC ";
        }
        if (isFinite(params.limit)) {
          sql += " LIMIT " + parseInt(params.limit, 10);
        }
      }

      return db.allAsync(sql, []).then(simpleMap);
    };

    DB.get = function (id) {
      var sql = "SELECT * FROM " + tablename + " WHERE " + idname + " = ?";
      var values = [id];

      return db.getAsync(sql, values).then(function (rows) {
        if (Array.isArray(rows)) {
          if (!rows.length) {
            return null;
          }

          return rows[0] || null;
        }

        return rows;
      }).then(simpleParse);
    };

    DB.upsert = function (id, data, oldId) {
      if (!data) {
        data = id;
        id = data[idnameCased];
      }

      return DB.set(oldId || id, data, oldId).then(function (result) {
        var success = result.changes >= 1;

        if (success) {
          return result;
        }

        return DB.create(id, data);
      });
    };

    DB.save = function (data, oldId) {
      if (!data[idnameCased] && !oldId) {
        // NOTE saving the id both in the object and the id for now
        data[idnameCased] = require('uuid').v4();
        return DB.create(data[idnameCased], data).then(function (/*stats*/) {
          //data._rowid = stats.id;
          return data;
        });
      }

      return DB.set(oldId || data[idnameCased], data, oldId).then(function (result) {
        var success = result.changes >= 1;

        if (success) {
          return result;
        } else {
          //console.log('[debug result of set]', result.sql);
          delete result.sql;
        }

        return null;
      });
    };

    DB.create = function (id, obj) {
      if (!obj) {
        obj = id;
        id = obj[idnameCased];
      }
      if (!id) {
        return PromiseA.reject(new Error("no id supplied"));
      }

      obj.createdAt = Date.now();
      obj.updatedAt = Date.now();

      return new PromiseA(function (resolve, reject) {
        var json = JSON.stringify(obj);
        var data = JSON.parse(json);

        var sql;

        // removes known fields from data
        sql = strainUpdate(id, data, function sqlTpl(fieldable) {
          return "INSERT INTO " + tablename + " (" + fieldable.join(', ') + ", " + idname + ")"
            //+ " VALUES ('" + vals.join("', '") + "')"
            + " VALUES (" + fieldable.map(function () { return '?'; }).join(", ") + ", ?)"
            ;
        });

        //console.log('[debug] DB.create() sql:', sql);
        db.run(sql, [], function (err) {
          if (err) {
            reject(err);
            return;
          }

          // NOTE changes is 1 even if the value of the updated record stays the same
          // (PostgreSQL would return 0 in that case)
          // thus if changes is 0 then it failed, otherwise it succeeded
          /*
          console.log('[log db wrapper insert]');
          console.log(this); // sql, lastID, changes
          console.log(this.sql);
          console.log('insert lastID', this.lastID); // sqlite's internal rowId
          console.log('insert changes', this.changes);
          */

          //this.id = id;
          resolve(this);
        });
      });
    };

    DB.set = function (id, obj, oldId) {
      obj.updatedAt = Date.now();

      var json = JSON.stringify(obj);
      var data = JSON.parse(json);

      return new PromiseA(function (resolve, reject) {
        function sqlTpl(fieldable) {
          // this will always at least have one fieldable value: json
          return "UPDATE " + tablename + " SET "
            + (fieldable.join(' = ?, ') + " = ?")
            + " WHERE " + idname + " = ?"
            ;
        }

        //var vals = [];
        // removes known fields from data
        data.updated_at = Date.now();
        var sql = strainUpdate(id, data/*, vals*/, sqlTpl, oldId);

        //console.log('[debug] DB.set() sql:', sql);
        db.run(sql, /*vals*/[], function (err) {
          //console.log('[debug] error:', err);
          if (err) {
            reject(err);
            return;
          }

          // it isn't possible to tell if the update succeeded or failed
          // only if the update resulted in a change or not
          /*
          console.log('[log db wrapper set]');
          console.log(this); // sql, lastID, changes
          console.log(this.sql);
          console.log('update lastID', this.lastID); // always 0 (except on INSERT)
          console.log('update changes', this.changes);
          */

          resolve(this);
        });
      });
    };

    DB.destroy = function (id) {
      if ('object' === typeof id) {
        id = id[idnameCased];
      }

      return new PromiseA(function (resolve, reject) {
        var sql = "DELETE FROM " + tablename + " WHERE " + idname + " = ?";
        var values = [id];

        db.run(sql, values, function (err) {
          if (err) {
            reject(err);
            return;
          }

          // it isn't possible to tell if the update succeeded or failed
          // only if the update resulted in a change or not
          /*
          console.log('[log db wrapper delete]');
          console.log(this); // sql, lastID, changes
          console.log(this.sql);
          console.log('delete lastID', this.lastID); // always 0 (except on INSERT)
          console.log('delete changes', this.changes);
          */

          resolve(this);
        });
      });
    };

    DB._db = db;

    return new PromiseA(function (resolve, reject) {
      var indexable = [idname + ' TEXT'];
      var sql;

      dir.indices.forEach(function (col) {
        if ('string' === typeof col) {
          col = { name: col, type: 'TEXT' };
        }
        if (!col.type) {
          col.type = 'TEXT';
        }
        indexable.push(
          db.escape(snakeCase(col.name))
        + ' ' + db.escape(col.type)
        );
      });
      indexable.push('json TEXT');

      sql = "CREATE TABLE IF NOT EXISTS '" + tablename + "' "
        + "(" + indexable.join(', ') + ", PRIMARY KEY(" + idname + "))"
        ;

      db.runAsync(sql).then(function () {
        sqlite3GetColumns(tablename, dir.indices, function (err) {
          if (err) {
            console.error('[Error] dbwrap get columns');
            console.error(err.stack);
            reject(err);
            return;
          }

          resolve(DB);
        });
      }, reject);
    });
  }

  if (!db.__masterquest_init) {
    db.__masterquest_init = true;
    db = PromiseA.promisifyAll(db);
    db.__masterquest_init = true;
    db.escape = function (str) {
      // TODO? literals for true,false,null
      // error on undefined?
      if (undefined === str) {
        str = '';
      }
      return String(str).replace(/'/g, "''");
    };

    if (dir && dir.verbose || db.verbose) {
      console.log('Getting Verbose up in here');
      db.on('trace', function (str) {
        console.log('SQL:', str);
      });

      db.on('profile', function (sql, ms) {
        console.log('Profile:', ms);
      });
    }
  }
  dbsMap.sql = db;

  dir.forEach(function (dir) {
    // TODO if directive is the same as existing dbsMap, skip it
    promises.push(createTable(dir).then(function (dbw) {

      dbsMap[dir.modelname] = dbw;

      return dbw;
    }));
  });

  return PromiseA.all(promises).then(function (/*dbs*/) {
    return dbsMap;
  });
}

module.exports.wrap = wrap;