'use strict';

// Quote an PostgreSQL identifier if ncecessary
function quote_identifier_if_needed (txt) {
    if (txt && !txt.match(/^[a-z_][a-z_0-9]*$/)) {
        return '"' + txt.replace(/\"/g, '""') + '"';
    } else {
        return txt;
    }
}

// Parse PostgreSQL table name (possibly quoted and with optional schema).+
// Returns { schema: 'schema_name', table: 'table_name' }
function parse_table_name (table) {
    function split_as_quoted_parts (table_name) {
        // parse table into 'parts' that may be quoted, each part
        // in the parts array being an object { part: 'text', quoted: false/true }
        var parts = [];
        var splitted = table_name.split(/\"/);
        for (var i = 0; i < splitted.length; i++) {
            if (splitted[i] === '') {
                if (parts.length > 0 && i < splitted.length - 1) {
                    i++;
                    parts[parts.length - 1].part += '"' + splitted[i];
                }
            } else {
                var is_quoted = (i > 0 && splitted[i - 1] === '') ||
                         (i < splitted.length - 1 && splitted[i + 1] === '');
                parts.push({ part: splitted[i], quoted: is_quoted });
            }
        }
        return parts;
    }

    var parts = split_as_quoted_parts(table);

    function split_single_part (part) {
        var schema_part = null;
        var table_part = null;
        if (part.quoted) {
            table_part = part.part;
        } else {
            var parts = part.part.split('.');
            if (parts.length === 1) {
                schema_part = null;
                table_part = parts[0];
            } else if (parts.length === 2) {
                schema_part = parts[0];
                table_part = parts[1];
            } // else invalid table name
        }
        return {
            schema: schema_part,
            table: table_part
        };
    }

    function split_two_parts (part1, part2) {
        var schema_part = null;
        var table_part = null;
        if (part1.quoted && !part2.quoted) {
            if (part2.part[0] === '.') {
                schema_part = part1.part;
                table_part = part2.part.slice(1);
            } // else invalid table name (missing dot)
        } else if (!part1.quoted && part2.quoted) {
            if (part1.part[part1.part.length - 1] === '.') {
                schema_part = part1.part.slice(0, -1);
                table_part = part2.part;
            } // else invalid table name (missing dot)
        } // else invalid table name (missing dot)
        return {
            schema: schema_part,
            table: table_part
        };
    }

    if (parts.length === 1) {
        return split_single_part(parts[0]);
    } else if (parts.length === 2) {
        return split_two_parts(parts[0], parts[1]);
    } else if (parts.length === 3 && parts[1].part === '.') {
        return {
            schema: parts[0].part,
            table: parts[2].part
        };
    } // else invalid table name
}

function table_identifier (parsed_name) {
    if (parsed_name && parsed_name.table) {
        if (parsed_name.schema) {
            return quote_identifier_if_needed(parsed_name.schema) + '.' + quote_identifier_if_needed(parsed_name.table);
        } else {
            return quote_identifier_if_needed(parsed_name.table);
        }
    } else {
        return null;
    }
}

module.exports = {
    parse: parse_table_name,
    quote: quote_identifier_if_needed,
    table_identifier: table_identifier
};