'use strict';

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 = {};
  }

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

  function lowerFirst(str) {
    return str.charAt(0).toLowerCase() + str.slice(1);
  }

  function snakeCase(str) {
    return lowerFirst(str).replace(
      /([A-Z])/g
    , function ($1) {
        return "_" + $1.toLowerCase();
      }
    );
  }

  function camelCase(str) {
    str = str.replace(
      /_([a-z])/g
    , function (g) {
        return g[1].toUpperCase();
      }
    );
    return str;
  }

  function upperCamelCase(str) {
    // TODO handle UTF-8 properly (use codePointAt, don't use slice)
    return str.charAt(0).toUpperCase() + camelCase(str).slice(1);
  }

  // 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(err.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 = PromiseA.promisifyAll(db);

    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);
      });
    }

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

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

    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);
          delete row.json;
        } else {
          obj = {};
        }

        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;
    }

    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 (obj && keys.length) {
        sql += 'WHERE ';

        keys.forEach(function (key, i) {
          if (i !== 0) {
            sql += 'AND ';
          }
          if (null === obj[key]) {
            sql += db.escape(snakeCase(key)) + " IS null";
          }
          else {
            // TODO check that key is some type? ignore undefined?
            sql += db.escape(snakeCase(key)) + " = '" + db.escape(obj[key]) + "'";
          }
        });
      }
      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 (params.orderBy) {
          sql += " ORDER BY \"" + db.escape(snakeCase(params.orderBy) + "\" ");
          if (params.orderByDesc) {
            sql += 'DESC ';
          }
        }
        if (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) {
      if (!data) {
        data = id;
        id = data[idnameCased];
      }

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

        if (success) {
          return result;
        }

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

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

      return DB.set(data[idnameCased], data).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);
        });
      });
    };

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

      delete data[idnameCased];

      if (!fieldable.length || Object.keys(data).length) {
        json = JSON.stringify(data);
        fieldable.push("json");
        //fieldable.push("json = '" + db.escape(json) + "'");
        vals.push(json);
      }

      vals.push(id);

      sql = cb(fieldable);

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

      while (vals.length) {
        sql = sql.replace(/\?/, "'" + db.escape(vals.shift()) + "'");
      }

      return sql;
    }

    DB.set = function (id, obj) {
      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);

        //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);
    });
  }

  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;
    }));
  });

  dbsMap.sql = db;

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

module.exports.wrap = wrap;