/*
 * Copyright 2016 Software Freedom Conservancy Inc.
 * Copyright 2016 Michael Gratton <mike@vee.net>
 *
 * This software is licensed under the GNU Lesser General Public License
 * (version 2.1 or later). See the COPYING file in this distribution.
 */

/**
 * Application logic for ComposerWebView.
 */
let ComposerPageState = function() {
    this.init.apply(this, arguments);
};
ComposerPageState.SPACE_CHAR_REGEX = /[\s]/i;
ComposerPageState.WORD_CHAR_REGEX = /[\s\\'!"#$%&()*+,\-.\/:;<=>?@\[\]^_`{|}~\u2000-\u206F\u2E00-\u2E7F]/i;
ComposerPageState.QUOTE_MARKER = "\x7f"; // delete
ComposerPageState.PROTOCOL_REGEX = /^(aim|apt|bitcoin|cvs|ed2k|ftp|file|finger|git|gtalk|http|https|irc|ircs|irc6|lastfm|ldap|ldaps|magnet|news|nntp|rsync|sftp|skype|smb|sms|svn|telnet|tftp|ssh|webcal|xmpp):/i;
// Taken from Geary.HTML.URL_REGEX, without the inline modifier (?x)
// at the start, which is unsupported in JS
ComposerPageState.URL_REGEX = new RegExp("\\b((?:[a-z][\\w-]+:(?:/{1,3}|[a-z0-9%])|www\\d{0,3}[.]|[a-z0-9.\\-]+[.][a-z]{2,4}/)(?:[^\\s()<>]+|\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\))+(?:\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\)|[^\\s`!()\\[\\]{};:'\".,<>?«»“”‘’]))", "gi");

ComposerPageState.prototype = {
    __proto__: PageState.prototype,
    init: function() {
        PageState.prototype.init.apply(this, []);
        this.bodyPart = null;
        this.signaturePart = null;
        this.quotePart = null;
        this.focusedPart = null;

        this.selections = new Map();
        this.nextSelectionId = 0;
        this.cursorContext = null;

        document.addEventListener("click", function(e) {
            if (e.target.tagName == "A") {
                e.preventDefault();
            }
        }, true);
    },
    loaded: function() {
        let state = this;

        this.bodyPart = document.getElementById("geary-body");
        if (this.bodyPart != null) {
            // Capture clicks on the document that aren't on an
            // existing part and prevent focus leaving it. Bug 779369.
            document.addEventListener("mousedown", function(e) {
                if (!state.containedInPart(e.target)) {
                    e.preventDefault();
                    e.stopPropagation();
                }
            });
        } else {
            // This happens if we are loading a draft created by a MUA
            // that isn't Geary, so we can't rely on any of the
            // expected HTML structure to be in place.
            this.bodyPart = document.body;
        }

        this.signaturePart = document.getElementById("geary-signature");
        this.quotePart = document.getElementById("geary-quote");

        // Should be using 'e.key' in listeners below instead of
        // keyIdentifier, but that was only fixed in WK in Oct 2016
        // (WK Bug 36267). Migrate to that when we can rely on it
        // being in WebKitGTK.
        document.body.addEventListener("keydown", function(e) {
            if (e.keyIdentifier == "U+0009" &&// Tab
                !e.ctrlKey && !e.altKey && !e.metaKey) {
                if (!e.shiftKey) {
                    state.tabOut();
                } else {
                    state.tabIn();
                }
                e.preventDefault();
            }
        });
        // We can't use keydown for this, captured or bubbled, since
        // that will also cause the line that the cursor is currently
        // positioned on when Enter is pressed to also be outdented.
        document.body.addEventListener("keyup", function(e) {
            if (e.keyIdentifier == "Enter" && !e.shiftKey) {
                // XXX WebKit seems to support both InsertNewline and
                // InsertNewlineInQuotedContent arguments for
                // execCommand, both of which sound like they would be
                // useful here. After a quick bit of testing neither
                // worked out of the box, so need to investigate
                // further. See:
                // https://github.com/WebKit/webkit/blob/master/Source/WebCore/editing/EditorCommand.cpp
                state.breakBlockquotes();
            }
        }, true);

        // Search for and remove a particular styling when we quote
        // text. If that style exists in the quoted text, we alter it
        // slightly so we don't mess with it later.
        let nodeList = document.querySelectorAll(
            "blockquote[style=\"margin: 0 0 0 40px; border: none; padding: 0px;\"]");
        for (let i = 0; i < nodeList.length; ++i) {
            nodeList.item(i).setAttribute(
                "style",
                "margin: 0 0 0 40px; padding: 0px; border:none;"
            );
        }

        // Focus within the HTML document
        document.body.focus();
        this.updateFocusClass(this.bodyPart);

        // Set text cursor at appropriate position
        let cursor = document.getElementById("cursormarker");
        if (cursor != null) {
            let range = document.createRange();
            range.selectNodeContents(cursor);
            range.collapse(false);

            let selection = window.getSelection();
            selection.removeAllRanges();
            selection.addRange(range);
            cursor.parentNode.removeChild(cursor);
        }


        // Enable editing only after modifying the body above.
        this.setEditable(true);

        PageState.prototype.loaded.apply(this, []);
    },
    setEditable: function(enabled) {
        if (!enabled) {
            this.stopBodyObserver();
        }

        this.bodyPart.contentEditable = true;
        if (this.signaturePart != null) {
            this.signaturePart.contentEditable = true;
        }
        if (this.quotePart != null) {
            this.quotePart.contentEditable = true;
        }

        if (enabled) {
            // Enable modification observation only after the document
            // has been set editable as WebKit will alter some attrs
            this.startBodyObserver();
        }
    },
    undo: function() {
        document.execCommand("undo", false, null);
        this.checkCommandStack();
    },
    redo: function() {
        document.execCommand("redo", false, null);
        this.checkCommandStack();
    },
    saveSelection: function() {
        let id = (++this.nextSelectionId).toString();
        this.selections.set(id, SelectionUtil.save());
        return id;
    },
    freeSelection: function(id) {
        this.selections.delete(id);
    },
    insertLink: function(href, selectionId) {
        SelectionUtil.restore(this.selections.get(selectionId));
        if (window.getSelection().isCollapsed) {
            // The saved selection was empty, which means that the user is
            // modifying an existing link instead of inserting a new one.
            let selection = SelectionUtil.save();
            let selected = SelectionUtil.getCursorElement();
            SelectionUtil.selectNode(selected);
            document.execCommand("createLink", false, href);
            SelectionUtil.restore(selection);
        } else {
            document.execCommand("createLink", false, href);
        }
    },
    deleteLink: function(selectionId) {
        SelectionUtil.restore(this.selections.get(selectionId));
        if (window.getSelection().isCollapsed) {
            // The saved selection was empty, which means that the user is
            // deleting the entire existing link.
            let selection = SelectionUtil.save();
            let selected = SelectionUtil.getCursorElement();
            SelectionUtil.selectNode(selected);
            document.execCommand("unlink", false, null);
            SelectionUtil.restore(selection);
        } else {
            document.execCommand("unlink", false, null);
        }
    },
    indentLine: function() {
        document.execCommand("indent", false, null);
        let nodeList = document.querySelectorAll(
            "blockquote[style=\"margin: 0 0 0 40px; border: none; padding: 0px;\"]"
        );
        for (let i = 0; i < nodeList.length; ++i) {
            let element = nodeList.item(i);
            element.removeAttribute("style");
            element.setAttribute("type", "cite");
        }
    },
    insertOrderedList: function() {
        document.execCommand("insertOrderedList", false, null);
    },
    insertUnorderedList: function() {
        document.execCommand("insertUnorderedList", false, null);
    },
    updateSignature: function(signature) {
        if (this.signaturePart != null) {
            if (signature.trim()) {
                this.signaturePart.innerHTML = signature;
                this.signaturePart.classList.remove("geary-no-display");
            } else {
                this.signaturePart.innerHTML = "";
                this.signaturePart.classList.add("geary-no-display");
            }
        }
    },
    deleteQuotedMessage: function() {
        if (this.quotePart != null) {
            this.quotePart.parentNode.removeChild(this.quotePart);
            this.quotePart = null;
        }
    },
    /**
     * Determines if subject or body content refers to attachments.
     */
    containsAttachmentKeyword: function(keywordSpec, subject) {
        let ATTACHMENT_KEYWORDS_SUFFIX = "doc|pdf|xls|ppt|rtf|pps";

        let completeKeys = new Set(keywordSpec.toLocaleLowerCase().split("|"));
        let suffixKeys = new Set(ATTACHMENT_KEYWORDS_SUFFIX.split("|"));

        // Check the subject line
        if (ComposerPageState.containsKeywords(subject, completeKeys, suffixKeys)) {
            return true;
        }

        // Check the body text
        let content = ComposerPageState.htmlToText(
            this.bodyPart, ["blockquote"]
        );
        return ComposerPageState.containsKeywords(
            content, completeKeys, suffixKeys
        );
    },
    tabOut: function() {
        document.execCommand(
            "inserthtml", false, "<span style='white-space: pre-wrap'>\t</span>"
        );
    },
    tabIn: function() {
        // If there is no selection and the character before the
        // text cursor is tab, delete it.
        let selection = window.getSelection();
        if (selection.isCollapsed) {
            selection.modify("extend", "backward", "character");
            if (selection.getRangeAt(0).toString() == "\t") {
                document.execCommand("delete", false, null);
            } else {
                selection.collapseToEnd();
            }
        }
    },
    breakBlockquotes: function() {
        // Do this in two phases to avoid in-line mutations caused by
        // execCommand affecting the DOM srtcuture
        let count = 0;
        let node = SelectionUtil.getCursorElement();
        while (node != document.body) {
            if (node.nodeName == "BLOCKQUOTE") {
                count++;
            }
            node = node.parentNode;
        }
        while (count > 0) {
            document.execCommand("outdent", false, null);
            count--;
        }
    },
    cleanContent: function() {
        // Prevent any modification signals being sent when mutating
        // the document below.
        this.stopBodyObserver();

        ComposerPageState.cleanPart(this.bodyPart, false);
        ComposerPageState.linkify(this.bodyPart);

        this.signaturePart = ComposerPageState.cleanPart(this.signaturePart, true);
        this.quotePart = ComposerPageState.cleanPart(this.quotePart, true);
    },
    getHtml: function() {
        // Clone the message parts so we can clean them without
        // modifiying the DOM, needed when saving drafts. In contrast
        // with cleanContent above, we don't remove empty elements so
        // they still exist when restoring from draft
        let parent = document.createElement("DIV");
        parent.appendChild(
            ComposerPageState.cleanPart(this.bodyPart.cloneNode(true), false)
        );

        if (this.signaturePart != null) {
            parent.appendChild(
                ComposerPageState.cleanPart(
                    this.signaturePart.cloneNode(true), false
                )
            );
        }

        if (this.quotePart != null) {
            parent.appendChild(
                ComposerPageState.cleanPart(
                    this.quotePart.cloneNode(true), false
                )
            );
        }

        return parent.innerHTML;
    },
    getText: function() {
        let text = ComposerPageState.htmlToText(document.body);
        return ComposerPageState.replaceNonBreakingSpace(text);
    },
    setRichText: function(enabled) {
        if (enabled) {
            document.body.classList.remove("plain");
        } else {
            document.body.classList.add("plain");
        }
    },
    selectionChanged: function() {
        PageState.prototype.selectionChanged.apply(this, []);

        let cursor = SelectionUtil.getCursorElement();

        // Update cursor context
        if (cursor != null) {
            let newContext = new EditContext(cursor);
            if (!newContext.equals(this.cursorContext)) {
                this.cursorContext = newContext;
                window.webkit.messageHandlers.cursorContextChanged.postMessage(
                    newContext.encode()
                );
            }
        }

        while (cursor != null) {
            let parent = cursor.parentNode;
            if (parent == document.body) {
                this.updateFocusClass(cursor);
                break;
            }
            cursor = parent;
        }
    },
    /**
     * Work around WebKit note yet supporting :focus-inside pseudoclass.
     */
    updateFocusClass: function(newFocus) {
        if (this.focusedPart != null) {
            this.focusedPart.classList.remove("geary-focus");
            this.focusedPart = null;
        }
        if (newFocus == this.bodyPart ||
            newFocus == this.signaturePart ||
            newFocus == this.quotePart) {
            this.focusedPart = newFocus;
            this.focusedPart.classList.add("geary-focus");
        }
    },
    containedInPart: function(target) {
        let inPart = false;
        for (let part of [this.bodyPart, this.quotePart, this.signaturePart]) {
            if (part != null && (part == target || part.contains(target))) {
                inPart = true;
                break;
            }
        }
        return inPart;
    }
};

/**
 * Determines if any keywords are present in a string.
 */
ComposerPageState.containsKeywords = function(line, wordKeys, suffixKeys) {
    let urlRegex = ComposerPageState.URL_REGEX;
    let lastToken = -1;
    let lastSpace = -1;
    for (var i = 0; i <= line.length; i++) {
        let char = (i < line.length) ? line[i] : " ";

        if (char.match(ComposerPageState.WORD_CHAR_REGEX)) {
            if (lastToken + 1 < i) {
                let wordToken = line.substring(lastToken + 1, i).toLocaleLowerCase();
                let isWordMatch = wordKeys.has(wordToken);
                let isSuffixMatch = suffixKeys.has(wordToken);
                if (isWordMatch || isSuffixMatch) {
                    let spaceToken = line.substring(lastSpace + 1, i);
                    let isUrl = (spaceToken.match(ComposerPageState.URL_REGEX) != null);

                    // Matches a token if it is a word that isn't in a
                    // URL. I.e. this gets "some attachment." but not
                    // "http://attachment.com"
                    if (isWordMatch && !isUrl) {
                        return true;
                    }

                    // Matches a token if it is a suffix that isn't a
                    // URL and such that the space-delimited token
                    // ends with ".SUFFIX". I.e. this matches "see
                    // attachment.pdf." but not
                    // "http://example.com/attachment.pdf" or "see the
                    // pdf."
                    if (isSuffixMatch &&
                        !isUrl &&
                        spaceToken.length != (1 + wordToken.length) &&
                        spaceToken.endsWith("." + wordToken)) {
                        return true;
                    }
                }
            }
            lastToken = i;

            if (char.match(ComposerPageState.SPACE_CHAR_REGEX)) {
                lastSpace = i;
            }
        }
    }
    return false;
};

/**
 * Removes internal attributes from a composer part..
 */
ComposerPageState.cleanPart = function(part, removeIfEmpty) {
    if (part != null) {
        part.removeAttribute("class");
        part.removeAttribute("contenteditable");

        if (removeIfEmpty && part.innerText.trim() == "") {
            part.parentNode.removeChild(part);
            part = null;
        }
    }
    return part;
};

/**
 * Gets plain text that adequately represents the information in the HTML
 *
 * Asterisks are inserted around bold text, slashes around italic text, and
 * underscores around underlined text. Link URLs are inserted after the link
 * text.
 *
 * Each line of a blockquote is prefixed with
 * `ComposerPageState.QUOTE_MARKER`, where the number of markers indicates
 * the depth of nesting of the quote.
 */
ComposerPageState.htmlToText = function(root, blacklist = []) {
    let parentStyle = window.getComputedStyle(root);
    let text = "";

    for (let node of (root.childNodes || [])) {
        let nodeName = node.nodeName.toLowerCase();
        if (blacklist.includes(nodeName)) {
            continue;
        }

        let isBlock = (
            node instanceof Element
                && window.getComputedStyle(node).display == "block"
                && node.innerText
        );
        if (isBlock) {
            // Make sure there's a newline before the element
            if (text != "" && text.substr(-1) != "\n") {
                text += "\n";
            }
        }
        switch (nodeName) {
            case "#text":
                let nodeText = node.nodeValue;
                switch (parentStyle.whiteSpace) {
                    case 'normal':
                    case 'nowrap':
                    case 'pre-line':
                        // Only space, tab, carriage return, and newline collapse
                        // https://www.w3.org/TR/2011/REC-CSS2-20110607/text.html#white-space-model
                        nodeText = nodeText.replace(/[ \t\r\n]+/g, " ");
                        if (nodeText == " " && " \t\r\n".includes(text.substr(-1)))
                            break; // There's already whitespace here
                        if (node == root.firstChild)
                            nodeText = nodeText.replace(/^ /, "");
                        if (node == root.lastChild)
                            nodeText = nodeText.replace(/ $/, "");
                        // Fall through
                    default:
                        text += nodeText;
                        break;
                }
                break;
            case "a":
                if (node.closest("body.plain")) {
                    text += ComposerPageState.htmlToText(node, blacklist);
                } else if (node.textContent == node.href) {
                    text += "<" + node.href + ">";
                } else {
                    text += ComposerPageState.htmlToText(node, blacklist);
                    text += " <" + node.href + ">";
                }
                break;
            case "b":
            case "strong":
                if (node.closest("body.plain")) {
                    text += ComposerPageState.htmlToText(node, blacklist);
                } else {
                    text += "*" + ComposerPageState.htmlToText(node, blacklist) + "*";
                }
                break;
            case "blockquote":
                let bqText = ComposerPageState.htmlToText(node, blacklist);
                // If there is a newline at the end of the quote, remove it
                // After this switch we ensure that there is a newline after the quote
                bqText = bqText.replace(/\n$/, "");
                let lines = bqText.split("\n");
                for (let i = 0; i < lines.length; i++)
                    lines[i] = ComposerPageState.QUOTE_MARKER + lines[i];
                text += lines.join("\n");
                break;
            case "br":
                text += "\n";
                break;
            case "i":
            case "em":
                if (node.closest("body.plain")) {
                    text += ComposerPageState.htmlToText(node, blacklist);
                } else {
                    text += "/" + ComposerPageState.htmlToText(node, blacklist) + "/";
                }
                break;
            case "u":
                if (node.closest("body.plain")) {
                    text += ComposerPageState.htmlToText(node, blacklist);
                } else {
                    text += "_" + ComposerPageState.htmlToText(node, blacklist) + "_";
                }
                break;
            case "#comment":
            case "style":
                break;
            default:
                text += ComposerPageState.htmlToText(node, blacklist);
                break;
        }
        if (isBlock) {
            // Ensure that the last character is a newline
            if (text.substr(-1) != "\n") {
                text += "\n";
            }
            if (node.nodeName.toLowerCase() == "p") {
                // Ensure that the last two characters are newlines
                if (text.substr(-2, 1) != "\n") {
                    text += "\n";
                }
            }
        }
    }

    return text;
};

// Linkifies "plain text" link
ComposerPageState.linkify = function(node) {
    if (node.nodeType == Node.TEXT_NODE) {
        while (node.nodeValue) {
            // Examine text node for something that looks like a URL
            let urlRegex = new RegExp(ComposerPageState.URL_REGEX);
            let url;
            do {
                let urlMatch = urlRegex.exec(node.nodeValue);
                if (!urlMatch) {
                    return;
                }
                url = urlMatch[0];
            } while (!url.match(ComposerPageState.PROTOCOL_REGEX));

            // We got one! Now split the text and swap in a new anchor.
            let before = node.nodeValue.substring(0, urlRegex.lastIndex - url.length);
            let after = node.nodeValue.substring(urlRegex.lastIndex);

            let beforeNode = document.createTextNode(before);
            let linkNode = document.createElement("A");
            linkNode.href = url;
            linkNode.textContent = url;
            let afterNode = document.createTextNode(after);

            let parentNode = node.parentNode;
            parentNode.insertBefore(beforeNode, node);
            parentNode.insertBefore(linkNode, node);
            parentNode.insertBefore(afterNode, node);
            parentNode.removeChild(node);

            // Keep searching for URLs after this one
            node = afterNode;
        }
    } else {
        // Recurse
        let child = node.firstChild;
        while (child != null) {
            // Save the child and get its next sibling early since if
            // it does actually contain a URL, it will be removed from
            // the tree
            let target = child;
            child = child.nextSibling;
            // Don't attempt to linkify existing links
            if (target.nodeName != "A") {
                ComposerPageState.linkify(target);
            }
        }
    }
};

/**
 * Converts all non-breaking space chars to plain spaces.
 */
ComposerPageState.replaceNonBreakingSpace = function(text) {
    // XXX this is a separate function for unit testing - since when
    // running as a unit test, HTMLElement.innerText appears to not
    // convert &nbsp into U+00A0.
    return text.replace(new RegExp(" ", "g"), " ");
};


/**
 * Encapsulates editing-related state for a specific DOM node.
 *
 * This must be kept in sync with the vala object of the same name.
 */
let EditContext = function() {
    this.init.apply(this, arguments);
};
EditContext.LINK_MASK = 1 << 0;

EditContext.prototype = {
    init: function(node) {
        this.context = 0;
        this.linkUrl = "";

        if (node.nodeName == "A") {
            this.context |=  EditContext.LINK_MASK;
            this.linkUrl = node.href;
        }

        let styles = window.getComputedStyle(node);
        let fontFamily = styles.getPropertyValue("font-family");
        if (["'", "\""].indexOf(fontFamily.charAt()) != -1) {
            fontFamily = fontFamily.substr(1, fontFamily.length - 2);
        }
        this.fontFamily = fontFamily;
        this.fontSize = styles.getPropertyValue("font-size").replace("px", "");
    },
    equals: function(other) {
        return other != null
            && this.context == other.context
            && this.linkUrl == other.linkUrl
            && this.fontFamily == other.fontFamily
            && this.fontSize == other.fontSize;
    },
    encode: function() {
        return [
            this.context.toString(16),
            this.linkUrl,
            this.fontFamily,
            this.fontSize
        ].join(",");
    }
};


/**
 * Utility methods for managing the DOM Selection.
 */
let SelectionUtil = {
    /**
     * Returns the element immediately under the text cursor.
     *
     * If there is a non-empty selection, the element at the end of the
     * selection is returned.
     */
    getCursorElement: function() {
        let selection = window.getSelection();
        let node = selection.focusNode;
        if (node != null && node.nodeType != Node.ELEMENT_NODE) {
            node = node.parentNode;
        }
        return node;
    },
    /**
     * Modifies the selection so that it contains the given target node.
     */
    selectNode: function(target) {
        let newRange = new Range();
        newRange.selectNode(target);

        let selection = window.getSelection();
        selection.removeAllRanges();
        selection.addRange(newRange);
    },
    /**
     * Saves the current selection so it can be restored with `restore`.
     */
    save: function() {
        let selection = window.getSelection();
        var ranges = [];
        let len = selection.rangeCount;
        for (let i = 0; i < len; ++i) {
            ranges.push(selection.getRangeAt(i));
        }
        return ranges;
    },
    /**
     * Restores the selection saved with `save`.
     */
    restore: function(saved) {
        let selection = window.getSelection();
        selection.removeAllRanges();
        for (let i = 0; i < saved.length; i++) {
            selection.addRange(saved[i]);
        }
    }
};


var geary = new ComposerPageState();
