// Copyright (C) 2007, Fredrik Kuivinen <frekui@gmail.com>
//               2007, Petr Baudis <pasky@suse.cz>
//          2008-2011, Jakub Narebski <jnareb@gmail.com>

/**
 * @fileOverview JavaScript side of Ajax-y 'blame_incremental' view in gitweb
 * @license GPLv2 or later
 */

/* ============================================================ */
/*
 * This code uses DOM methods instead of (nonstandard) innerHTML
 * to modify page.
 *
 * innerHTML is non-standard IE extension, though supported by most
 * browsers; however Firefox up to version 1.5 didn't implement it in
 * a strict mode (application/xml+xhtml mimetype).
 *
 * Also my simple benchmarks show that using elem.firstChild.data =
 * 'content' is slightly faster than elem.innerHTML = 'content'.  It
 * is however more fragile (text element fragment must exists), and
 * less feature-rich (we cannot add HTML).
 *
 * Note that DOM 2 HTML is preferred over generic DOM 2 Core; the
 * equivalent using DOM 2 Core is usually shown in comments.
 */


/* ............................................................ */
/* utility/helper functions (and variables) */

var xhr;        // XMLHttpRequest object
var projectUrl; // partial query + separator ('?' or ';')

// 'commits' is an associative map. It maps SHA1s to Commit objects.
var commits = {};

/**
 * constructor for Commit objects, used in 'blame'
 * @class Represents a blamed commit
 * @param {String} sha1: SHA-1 identifier of a commit
 */
function Commit(sha1) {
        if (this instanceof Commit) {
                this.sha1 = sha1;
                this.nprevious = 0; /* number of 'previous', effective parents */
        } else {
                return new Commit(sha1);
        }
}

/* ............................................................ */
/* progress info, timing, error reporting */

var blamedLines = 0;
var totalLines  = '???';
var div_progress_bar;
var div_progress_info;

/**
 * Detects how many lines does a blamed file have,
 * This information is used in progress info
 *
 * @returns {Number|String} Number of lines in file, or string '...'
 */
function countLines() {
        var table =
                document.getElementById('blame_table') ||
                document.getElementsByTagName('table')[0];

        if (table) {
                return table.getElementsByTagName('tr').length - 1; // for header
        } else {
                return '...';
        }
}

/**
 * update progress info and length (width) of progress bar
 *
 * @globals div_progress_info, div_progress_bar, blamedLines, totalLines
 */
function updateProgressInfo() {
        if (!div_progress_info) {
                div_progress_info = document.getElementById('progress_info');
        }
        if (!div_progress_bar) {
                div_progress_bar = document.getElementById('progress_bar');
        }
        if (!div_progress_info && !div_progress_bar) {
                return;
        }

        var percentage = Math.floor(100.0*blamedLines/totalLines);

        if (div_progress_info) {
                div_progress_info.firstChild.data  = blamedLines + ' / ' + totalLines +
                        ' (' + padLeftStr(percentage, 3, '\u00A0') + '%)';
        }

        if (div_progress_bar) {
                //div_progress_bar.setAttribute('style', 'width: '+percentage+'%;');
                div_progress_bar.style.width = percentage + '%';
        }
}


var t_interval_server = '';
var cmds_server = '';
var t0 = new Date();

/**
 * write how much it took to generate data, and to run script
 *
 * @globals t0, t_interval_server, cmds_server
 */
function writeTimeInterval() {
        var info_time = document.getElementById('generating_time');
        if (!info_time || !t_interval_server) {
                return;
        }
        var t1 = new Date();
        info_time.firstChild.data += ' + (' +
                t_interval_server + ' sec server blame_data / ' +
                (t1.getTime() - t0.getTime())/1000 + ' sec client JavaScript)';

        var info_cmds = document.getElementById('generating_cmd');
        if (!info_time || !cmds_server) {
                return;
        }
        info_cmds.firstChild.data += ' + ' + cmds_server;
}

/**
 * show an error message alert to user within page (in progress info area)
 * @param {String} str: plain text error message (no HTML)
 *
 * @globals div_progress_info
 */
function errorInfo(str) {
        if (!div_progress_info) {
                div_progress_info = document.getElementById('progress_info');
        }
        if (div_progress_info) {
                div_progress_info.className = 'error';
                div_progress_info.firstChild.data = str;
        }
}

/* ............................................................ */
/* coloring rows during blame_data (git blame --incremental) run */

/**
 * used to extract N from 'colorN', where N is a number,
 * @constant
 */
var colorRe = /\bcolor([0-9]*)\b/;

/**
 * return N if <tr class="colorN">, otherwise return null
 * (some browsers require CSS class names to begin with letter)
 *
 * @param {HTMLElement} tr: table row element to check
 * @param {String} tr.className: 'class' attribute of tr element
 * @returns {Number|null} N if tr.className == 'colorN', otherwise null
 *
 * @globals colorRe
 */
function getColorNo(tr) {
        if (!tr) {
                return null;
        }
        var className = tr.className;
        if (className) {
                var match = colorRe.exec(className);
                if (match) {
                        return parseInt(match[1], 10);
                }
        }
        return null;
}

var colorsFreq = [0, 0, 0];
/**
 * return one of given possible colors (currently least used one)
 * example: chooseColorNoFrom(2, 3) returns 2 or 3
 *
 * @param {Number[]} arguments: one or more numbers
 *        assumes that  1 <= arguments[i] <= colorsFreq.length
 * @returns {Number} Least used color number from arguments
 * @globals colorsFreq
 */
function chooseColorNoFrom() {
        // choose the color which is least used
        var colorNo = arguments[0];
        for (var i = 1; i < arguments.length; i++) {
                if (colorsFreq[arguments[i]-1] < colorsFreq[colorNo-1]) {
                        colorNo = arguments[i];
                }
        }
        colorsFreq[colorNo-1]++;
        return colorNo;
}

/**
 * given two neighbor <tr> elements, find color which would be different
 * from color of both of neighbors; used to 3-color blame table
 *
 * @param {HTMLElement} tr_prev
 * @param {HTMLElement} tr_next
 * @returns {Number} color number N such that
 * colorN != tr_prev.className && colorN != tr_next.className
 */
function findColorNo(tr_prev, tr_next) {
        var color_prev = getColorNo(tr_prev);
        var color_next = getColorNo(tr_next);


        // neither of neighbors has color set
        // THEN we can use any of 3 possible colors
        if (!color_prev && !color_next) {
                return chooseColorNoFrom(1,2,3);
        }

        // either both neighbors have the same color,
        // or only one of neighbors have color set
        // THEN we can use any color except given
        var color;
        if (color_prev === color_next) {
                color = color_prev; // = color_next;
        } else if (!color_prev) {
                color = color_next;
        } else if (!color_next) {
                color = color_prev;
        }
        if (color) {
                return chooseColorNoFrom((color % 3) + 1, ((color+1) % 3) + 1);
        }

        // neighbors have different colors
        // THEN there is only one color left
        return (3 - ((color_prev + color_next) % 3));
}

/* ............................................................ */
/* coloring rows like 'blame' after 'blame_data' finishes */

/**
 * returns true if given row element (tr) is first in commit group
 * to be used only after 'blame_data' finishes (after processing)
 *
 * @param {HTMLElement} tr: table row
 * @returns {Boolean} true if TR is first in commit group
 */
function isStartOfGroup(tr) {
        return tr.firstChild.className === 'sha1';
}

/**
 * change colors to use zebra coloring (2 colors) instead of 3 colors
 * concatenate neighbor commit groups belonging to the same commit
 *
 * @globals colorRe
 */
function fixColorsAndGroups() {
        var colorClasses = ['light', 'dark'];
        var linenum = 1;
        var tr, prev_group;
        var colorClass = 0;
        var table =
                document.getElementById('blame_table') ||
                document.getElementsByTagName('table')[0];

        while ((tr = document.getElementById('l'+linenum))) {
        // index origin is 0, which is table header; start from 1
        //while ((tr = table.rows[linenum])) { // <- it is slower
                if (isStartOfGroup(tr, linenum, document)) {
                        if (prev_group &&
                            prev_group.firstChild.firstChild.href ===
                                    tr.firstChild.firstChild.href) {
                                // we have to concatenate groups
                                var prev_rows = prev_group.firstChild.rowSpan || 1;
                                var curr_rows =         tr.firstChild.rowSpan || 1;
                                prev_group.firstChild.rowSpan = prev_rows + curr_rows;
                                //tr.removeChild(tr.firstChild);
                                tr.deleteCell(0); // DOM2 HTML way
                        } else {
                                colorClass = (colorClass + 1) % 2;
                                prev_group = tr;
                        }
                }
                var tr_class = tr.className;
                tr.className = tr_class.replace(colorRe, colorClasses[colorClass]);
                linenum++;
        }
}


/* ============================================================ */
/* main part: parsing response */

/**
 * Function called for each blame entry, as soon as it finishes.
 * It updates page via DOM manipulation, adding sha1 info, etc.
 *
 * @param {Commit} commit: blamed commit
 * @param {Object} group: object representing group of lines,
 *                        which blame the same commit (blame entry)
 *
 * @globals blamedLines
 */
function handleLine(commit, group) {
        /*
           This is the structure of the HTML fragment we are working
           with:

           <tr id="l123" class="">
             <td class="sha1" title=""><a href=""> </a></td>
             <td class="linenr"><a class="linenr" href="">123</a></td>
             <td class="pre"># times (my ext3 doesn&#39;t).</td>
           </tr>
        */

        var resline = group.resline;

        // format date and time string only once per commit
        if (!commit.info) {
                /* e.g. 'Kay Sievers, 2005-08-07 21:49:46 +0200' */
                commit.info = commit.author + ', ' +
                        formatDateISOLocal(commit.authorTime, commit.authorTimezone);
        }

        // color depends on group of lines, not only on blamed commit
        var colorNo = findColorNo(
                document.getElementById('l'+(resline-1)),
                document.getElementById('l'+(resline+group.numlines))
        );

        // loop over lines in commit group
        for (var i = 0; i < group.numlines; i++, resline++) {
                var tr = document.getElementById('l'+resline);
                if (!tr) {
                        break;
                }
                /*
                        <tr id="l123" class="">
                          <td class="sha1" title=""><a href=""> </a></td>
                          <td class="linenr"><a class="linenr" href="">123</a></td>
                          <td class="pre"># times (my ext3 doesn&#39;t).</td>
                        </tr>
                */
                var td_sha1  = tr.firstChild;
                var a_sha1   = td_sha1.firstChild;
                var a_linenr = td_sha1.nextSibling.firstChild;

                /* <tr id="l123" class=""> */
                var tr_class = '';
                if (colorNo !== null) {
                        tr_class = 'color'+colorNo;
                }
                if (commit.boundary) {
                        tr_class += ' boundary';
                }
                if (commit.nprevious === 0) {
                        tr_class += ' no-previous';
                } else if (commit.nprevious > 1) {
                        tr_class += ' multiple-previous';
                }
                tr.className = tr_class;

                /* <td class="sha1" title="?" rowspan="?"><a href="?">?</a></td> */
                if (i === 0) {
                        td_sha1.title = commit.info;
                        td_sha1.rowSpan = group.numlines;

                        a_sha1.href = projectUrl + 'a=commit;h=' + commit.sha1;
                        if (a_sha1.firstChild) {
                                a_sha1.firstChild.data = commit.sha1.substr(0, 8);
                        } else {
                                a_sha1.appendChild(
                                        document.createTextNode(commit.sha1.substr(0, 8)));
                        }
                        if (group.numlines >= 2) {
                                var fragment = document.createDocumentFragment();
                                var br   = document.createElement("br");
                                var match = commit.author.match(/\b([A-Z])\B/g);
                                if (match) {
                                        var text = document.createTextNode(
                                                        match.join(''));
                                }
                                if (br && text) {
                                        var elem = fragment || td_sha1;
                                        elem.appendChild(br);
                                        elem.appendChild(text);
                                        if (fragment) {
                                                td_sha1.appendChild(fragment);
                                        }
                                }
                        }
                } else {
                        //tr.removeChild(td_sha1); // DOM2 Core way
                        tr.deleteCell(0); // DOM2 HTML way
                }

                /* <td class="linenr"><a class="linenr" href="?">123</a></td> */
                var linenr_commit =
                        ('previous' in commit ? commit.previous : commit.sha1);
                var linenr_filename =
                        ('file_parent' in commit ? commit.file_parent : commit.filename);
                a_linenr.href = projectUrl + 'a=blame_incremental' +
                        ';hb=' + linenr_commit +
                        ';f='  + encodeURIComponent(linenr_filename) +
                        '#l' + (group.srcline + i);

                blamedLines++;

                //updateProgressInfo();
        }
}

// ----------------------------------------------------------------------

/**#@+
 * @constant
 */
var sha1Re = /^([0-9a-f]{40}) ([0-9]+) ([0-9]+) ([0-9]+)/;
var infoRe = /^([a-z-]+) ?(.*)/;
var endRe  = /^END ?([^ ]*) ?(.*)/;
/**@-*/

var curCommit = new Commit();
var curGroup  = {};

var pollTimer = null;

/**
 * Parse output from 'git blame --incremental [...]', received via
 * XMLHttpRequest from server (blamedataUrl), and call handleLine
 * (which updates page) as soon as blame entry is completed.
 *
 * @param {String[]} lines: new complete lines from blamedata server
 *
 * @globals commits, curCommit, curGroup, t_interval_server, cmds_server
 * @globals sha1Re, infoRe, endRe
 */
function processBlameLines(lines) {
        var match;

        for (var i = 0, len = lines.length; i < len; i++) {

                if ((match = sha1Re.exec(lines[i]))) {
                        var sha1 = match[1];
                        var srcline  = parseInt(match[2], 10);
                        var resline  = parseInt(match[3], 10);
                        var numlines = parseInt(match[4], 10);

                        var c = commits[sha1];
                        if (!c) {
                                c = new Commit(sha1);
                                commits[sha1] = c;
                        }
                        curCommit = c;

                        curGroup.srcline = srcline;
                        curGroup.resline = resline;
                        curGroup.numlines = numlines;

                } else if ((match = infoRe.exec(lines[i]))) {
                        var info = match[1];
                        var data = match[2];
                        switch (info) {
                        case 'filename':
                                curCommit.filename = unquote(data);
                                // 'filename' information terminates the entry
                                handleLine(curCommit, curGroup);
                                updateProgressInfo();
                                break;
                        case 'author':
                                curCommit.author = data;
                                break;
                        case 'author-time':
                                curCommit.authorTime = parseInt(data, 10);
                                break;
                        case 'author-tz':
                                curCommit.authorTimezone = data;
                                break;
                        case 'previous':
                                curCommit.nprevious++;
                                // store only first 'previous' header
                                if (!'previous' in curCommit) {
                                        var parts = data.split(' ', 2);
                                        curCommit.previous    = parts[0];
                                        curCommit.file_parent = unquote(parts[1]);
                                }
                                break;
                        case 'boundary':
                                curCommit.boundary = true;
                                break;
                        } // end switch

                } else if ((match = endRe.exec(lines[i]))) {
                        t_interval_server = match[1];
                        cmds_server = match[2];

                } else if (lines[i] !== '') {
                        // malformed line

                } // end if (match)

        } // end for (lines)
}

/**
 * Process new data and return pointer to end of processed part
 *
 * @param {String} unprocessed: new data (from nextReadPos)
 * @param {Number} nextReadPos: end of last processed data
 * @return {Number} end of processed data (new value for nextReadPos)
 */
function processData(unprocessed, nextReadPos) {
        var lastLineEnd = unprocessed.lastIndexOf('\n');
        if (lastLineEnd !== -1) {
                var lines = unprocessed.substring(0, lastLineEnd).split('\n');
                nextReadPos += lastLineEnd + 1 /* 1 == '\n'.length */;

                processBlameLines(lines);
        } // end if

        return nextReadPos;
}

/**
 * Handle XMLHttpRequest errors
 *
 * @param {XMLHttpRequest} xhr: XMLHttpRequest object
 *
 * @globals pollTimer, commits
 */
function handleError(xhr) {
        errorInfo('Server error: ' +
                xhr.status + ' - ' + (xhr.statusText || 'Error contacting server'));

        clearInterval(pollTimer);
        commits = {}; // free memory
}

/**
 * Called after XMLHttpRequest finishes (loads)
 *
 * @param {XMLHttpRequest} xhr: XMLHttpRequest object (unused)
 *
 * @globals pollTimer, commits
 */
function responseLoaded(xhr) {
        clearInterval(pollTimer);

        fixColorsAndGroups();
        writeTimeInterval();
        commits = {}; // free memory
}

/**
 * handler for XMLHttpRequest onreadystatechange event
 * @see startBlame
 *
 * @globals xhr
 */
function handleResponse() {

        /*
         * xhr.readyState
         *
         *  Value  Constant (W3C)    Description
         *  -------------------------------------------------------------------
         *  0      UNSENT            open() has not been called yet.
         *  1      OPENED            send() has not been called yet.
         *  2      HEADERS_RECEIVED  send() has been called, and headers
         *                           and status are available.
         *  3      LOADING           Downloading; responseText holds partial data.
         *  4      DONE              The operation is complete.
         */

        if (xhr.readyState !== 4 && xhr.readyState !== 3) {
                return;
        }

        // the server returned error
        // try ... catch block is to work around bug in IE8
        try {
                if (xhr.readyState === 3 && xhr.status !== 200) {
                        return;
                }
        } catch (e) {
                return;
        }
        if (xhr.readyState === 4 && xhr.status !== 200) {
                handleError(xhr);
                return;
        }

        // In konqueror xhr.responseText is sometimes null here...
        if (xhr.responseText === null) {
                return;
        }

        // extract new whole (complete) lines, and process them
        while (xhr.prevDataLength !== xhr.responseText.length) {
                if (xhr.readyState === 4 &&
                    xhr.prevDataLength === xhr.responseText.length) {
                        break;
                }

                xhr.prevDataLength = xhr.responseText.length;
                var unprocessed = xhr.responseText.substring(xhr.nextReadPos);
                xhr.nextReadPos = processData(unprocessed, xhr.nextReadPos);
        } // end while

        // did we finish work?
        if (xhr.readyState === 4 &&
            xhr.prevDataLength === xhr.responseText.length) {
                responseLoaded(xhr);
        }
}

// ============================================================
// ------------------------------------------------------------

/**
 * Incrementally update line data in blame_incremental view in gitweb.
 *
 * @param {String} blamedataUrl: URL to server script generating blame data.
 * @param {String} bUrl: partial URL to project, used to generate links.
 *
 * Called from 'blame_incremental' view after loading table with
 * file contents, a base for blame view.
 *
 * @globals xhr, t0, projectUrl, div_progress_bar, totalLines, pollTimer
*/
function startBlame(blamedataUrl, bUrl) {

        xhr = createRequestObject();
        if (!xhr) {
                errorInfo('ERROR: XMLHttpRequest not supported');
                return;
        }

        t0 = new Date();
        projectUrl = bUrl + (bUrl.indexOf('?') === -1 ? '?' : ';');
        if ((div_progress_bar = document.getElementById('progress_bar'))) {
                //div_progress_bar.setAttribute('style', 'width: 100%;');
                div_progress_bar.style.cssText = 'width: 100%;';
        }
        totalLines = countLines();
        updateProgressInfo();

        /* add extra properties to xhr object to help processing response */
        xhr.prevDataLength = -1;  // used to detect if we have new data
        xhr.nextReadPos = 0;      // where unread part of response starts

        xhr.onreadystatechange = handleResponse;
        //xhr.onreadystatechange = function () { handleResponse(xhr); };

        xhr.open('GET', blamedataUrl);
        xhr.setRequestHeader('Accept', 'text/plain');
        xhr.send(null);

        // not all browsers call onreadystatechange event on each server flush
        // poll response using timer every second to handle this issue
        pollTimer = setInterval(xhr.onreadystatechange, 1000);
}

/* end of blame_incremental.js */