'use strict';

var path = require('path')
  , Stream = require('stream').Stream
  , Split = require('split')
  , util = require('util')
  , defaultPort = 5432
  , isWin = (process.platform === 'win32')
  , warnStream = process.stderr
;


var S_IRWXG = 56     //    00070(8)
  , S_IRWXO = 7      //    00007(8)
  , S_IFMT  = 61440  // 00170000(8)
  , S_IFREG = 32768  //  0100000(8)
;
function isRegFile(mode) {
    return ((mode & S_IFMT) == S_IFREG);
}

var fieldNames = [ 'host', 'port', 'database', 'user', 'password' ];
var nrOfFields = fieldNames.length;
var passKey = fieldNames[ nrOfFields -1 ];


function warn() {
    var isWritable = (
        warnStream instanceof Stream &&
          true === warnStream.writable
    );

    if (isWritable) {
        var args = Array.prototype.slice.call(arguments).concat("\n");
        warnStream.write( util.format.apply(util, args) );
    }
}


Object.defineProperty(module.exports, 'isWin', {
    get : function() {
        return isWin;
    } ,
    set : function(val) {
        isWin = val;
    }
});


module.exports.warnTo = function(stream) {
    var old = warnStream;
    warnStream = stream;
    return old;
};

module.exports.getFileName = function(env){
    env = env || process.env;
    var file = env.PGPASSFILE || (
        isWin ?
          path.join( env.APPDATA , 'postgresql', 'pgpass.conf' ) :
          path.join( env.HOME, '.pgpass' )
    );
    return file;
};

module.exports.usePgPass = function(stats, fname) {
    if (Object.prototype.hasOwnProperty.call(process.env, 'PGPASSWORD')) {
        return false;
    }

    if (isWin) {
        return true;
    }

    fname = fname || '<unkn>';

    if (! isRegFile(stats.mode)) {
        warn('WARNING: password file "%s" is not a plain file', fname);
        return false;
    }

    if (stats.mode & (S_IRWXG | S_IRWXO)) {
        /* If password file is insecure, alert the user and ignore it. */
        warn('WARNING: password file "%s" has group or world access; permissions should be u=rw (0600) or less', fname);
        return false;
    }

    return true;
};


var matcher = module.exports.match = function(connInfo, entry) {
    return fieldNames.slice(0, -1).reduce(function(prev, field, idx){
        if (idx == 1) {
            // the port
            if ( Number( connInfo[field] || defaultPort ) === Number( entry[field] ) ) {
                return prev && true;
            }
        }
        return prev && (
            entry[field] === '*' ||
              entry[field] === connInfo[field]
        );
    }, true);
};


module.exports.getPassword = function(connInfo, stream, cb) {
    var pass;
    var lineStream = stream.pipe(new Split());

    function onLine(line) {
        var entry = parseLine(line);
        if (entry && isValidEntry(entry) && matcher(connInfo, entry)) {
            pass = entry[passKey];
            lineStream.end(); // -> calls onEnd(), but pass is set now
        }
    }

    var onEnd = function() {
        stream.destroy();
        cb(pass);
    };

    var onErr = function(err) {
        stream.destroy();
        warn('WARNING: error on reading file: %s', err);
        cb(undefined);
    };

    stream.on('error', onErr);
    lineStream
        .on('data', onLine)
        .on('end', onEnd)
        .on('error', onErr)
    ;

};


var parseLine = module.exports.parseLine = function(line) {
    if (line.length < 11 || line.match(/^\s+#/)) {
        return null;
    }

    var curChar = '';
    var prevChar = '';
    var fieldIdx = 0;
    var startIdx = 0;
    var endIdx = 0;
    var obj = {};
    var isLastField = false;
    var addToObj = function(idx, i0, i1) {
        var field = line.substring(i0, i1);

        if (! Object.hasOwnProperty.call(process.env, 'PGPASS_NO_DEESCAPE')) {
            field = field.replace(/\\([:\\])/g, '$1');
        }

        obj[ fieldNames[idx] ] = field;
    };

    for (var i = 0 ; i < line.length-1 ; i += 1) {
        curChar = line.charAt(i+1);
        prevChar = line.charAt(i);

        isLastField = (fieldIdx == nrOfFields-1);

        if (isLastField) {
            addToObj(fieldIdx, startIdx);
            break;
        }

        if (i >= 0 && curChar == ':' && prevChar !== '\\') {
            addToObj(fieldIdx, startIdx, i+1);

            startIdx = i+2;
            fieldIdx += 1;
        }
    }

    obj = ( Object.keys(obj).length === nrOfFields ) ? obj : null;

    return obj;
};


var isValidEntry = module.exports.isValidEntry = function(entry){
    var rules = {
        // host
        0 : function(x){
            return x.length > 0;
        } ,
        // port
        1 : function(x){
            if (x === '*') {
                return true;
            }
            x = Number(x);
            return (
                isFinite(x) &&
                  x > 0 &&
                  x < 9007199254740992 &&
                  Math.floor(x) === x
            );
        } ,
        // database
        2 : function(x){
            return x.length > 0;
        } ,
        // username
        3 : function(x){
            return x.length > 0;
        } ,
        // password
        4 : function(x){
            return x.length > 0;
        }
    };

    for (var idx = 0 ; idx < fieldNames.length ; idx += 1) {
        var rule = rules[idx];
        var value = entry[ fieldNames[idx] ] || '';

        var res = rule(value);
        if (!res) {
            return false;
        }
    }

    return true;
};