// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: https://codemirror.net/LICENSE

;(function (mod) {
    if (typeof exports == 'object' && typeof module == 'object')
        // CommonJS
        mod(require('../../lib/codemirror'))
    else if (typeof define == 'function' && define.amd)
        // AMD
        define(['../../lib/codemirror'], mod)
    // Plain browser env
    else mod(CodeMirror)
})(function (CodeMirror) {
    'use strict'

    var rfc2822 = [
        'From',
        'Sender',
        'Reply-To',
        'To',
        'Cc',
        'Bcc',
        'Message-ID',
        'In-Reply-To',
        'References',
        'Resent-From',
        'Resent-Sender',
        'Resent-To',
        'Resent-Cc',
        'Resent-Bcc',
        'Resent-Message-ID',
        'Return-Path',
        'Received',
    ]
    var rfc2822NoEmail = ['Date', 'Subject', 'Comments', 'Keywords', 'Resent-Date']

    CodeMirror.registerHelper('hintWords', 'mbox', rfc2822.concat(rfc2822NoEmail))

    var whitespace = /^[ \t]/
    var separator = /^From / // See RFC 4155
    var rfc2822Header = new RegExp('^(' + rfc2822.join('|') + '): ')
    var rfc2822HeaderNoEmail = new RegExp('^(' + rfc2822NoEmail.join('|') + '): ')
    var header = /^[^:]+:/ // Optional fields defined in RFC 2822
    var email = /^[^ ]+@[^ ]+/
    var untilEmail = /^.*?(?=[^ ]+?@[^ ]+)/
    var bracketedEmail = /^<.*?>/
    var untilBracketedEmail = /^.*?(?=<.*>)/

    function styleForHeader(header) {
        if (header === 'Subject') return 'header'
        return 'string'
    }

    function readToken(stream, state) {
        if (stream.sol()) {
            // From last line
            state.inSeparator = false
            if (state.inHeader && stream.match(whitespace)) {
                // Header folding
                return null
            } else {
                state.inHeader = false
                state.header = null
            }

            if (stream.match(separator)) {
                state.inHeaders = true
                state.inSeparator = true
                return 'atom'
            }

            var match
            var emailPermitted = false
            if ((match = stream.match(rfc2822HeaderNoEmail)) || ((emailPermitted = true) && (match = stream.match(rfc2822Header)))) {
                state.inHeaders = true
                state.inHeader = true
                state.emailPermitted = emailPermitted
                state.header = match[1]
                return 'atom'
            }

            // Use vim's heuristics: recognize custom headers only if the line is in a
            // block of legitimate headers.
            if (state.inHeaders && (match = stream.match(header))) {
                state.inHeader = true
                state.emailPermitted = true
                state.header = match[1]
                return 'atom'
            }

            state.inHeaders = false
            stream.skipToEnd()
            return null
        }

        if (state.inSeparator) {
            if (stream.match(email)) return 'link'
            if (stream.match(untilEmail)) return 'atom'
            stream.skipToEnd()
            return 'atom'
        }

        if (state.inHeader) {
            var style = styleForHeader(state.header)

            if (state.emailPermitted) {
                if (stream.match(bracketedEmail)) return style + ' link'
                if (stream.match(untilBracketedEmail)) return style
            }
            stream.skipToEnd()
            return style
        }

        stream.skipToEnd()
        return null
    }

    CodeMirror.defineMode('mbox', function () {
        return {
            startState: function () {
                return {
                    // Is in a mbox separator
                    inSeparator: false,
                    // Is in a mail header
                    inHeader: false,
                    // If bracketed email is permitted. Only applicable when inHeader
                    emailPermitted: false,
                    // Name of current header
                    header: null,
                    // Is in a region of mail headers
                    inHeaders: false,
                }
            },
            token: readToken,
            blankLine: function (state) {
                state.inHeaders = state.inSeparator = state.inHeader = false
            },
        }
    })

    CodeMirror.defineMIME('application/mbox', 'mbox')
})