/**
 * This file is part of Haketilo.
 *
 * Function: Install mappings/resources in Haketilo.
 *
 * Copyright (C) 2022 Wojtek Kosior
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute forms of that code without the copy of the GNU
 * GPL normally required by section 4, provided you include this
 * license notice and, in case of non-source distribution, a URL
 * through which recipients can access the Corresponding Source.
 * If you modify file(s) with this exception, you may extend this
 * exception to your version of the file(s), but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * As a special exception to the GPL, any HTML file which merely
 * makes function calls to this code, and for that purpose
 * includes it by reference shall be deemed a separate work for
 * copyright law purposes. If you modify this code, you may extend
 * this exception to your version of the code, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
 * license. Although I request that you do not make use of this code in a
 * proprietary program, I am not going to enforce this in court.
 */

#IMPORT common/indexeddb.js AS haketilodb
#IMPORT html/dialog.js
#IMPORT html/item_preview.js AS ip

#FROM common/browser.js    IMPORT browser
#FROM html/DOM_helpers.js  IMPORT clone_template, Showable
#FROM common/entities.js   IMPORT item_id_string, version_string, get_files
#FROM common/misc.js       IMPORT sha256_async AS compute_sha256
#FROM common/jsonschema.js IMPORT haketilo_validator, haketilo_schemas
#FROM common/entities.js   IMPORT parse_schema_uri

#FROM html/repo_query_cacher_client.js IMPORT indirect_fetch

const coll = new Intl.Collator();

/*
 * Comparator used to sort items in the order we want them to appear in
 * install dialog: first mappings alphabetically, then resources alphabetically.
 */
function compare_items(def1, def2) {
    if (def1.type !== def2.type)
	return def1.type === "mapping" ? -1 : 1;

    const name_comparison = coll.compare(def1.long_name, def2.long_name);
    return name_comparison === 0 ?
	coll.compare(def1.identifier, def2.identifier) : name_comparison;
}

function ItemEntry(install_view, item) {
    Object.assign(this, clone_template("install_list_entry"));
    this.item_def = item.def;

    this.item_name.innerText = item.def.long_name;
    this.item_id.innerText = item_id_string(item.def);
    if (item.db_def) {
	this.old_ver.innerText =
	    version_string(item.db_def.version, item.db_def.revision);
	this.update_info.classList.remove("hide");
    }

    let preview_cb = () => install_view.preview_item(item.def);
    preview_cb = install_view.dialog_ctx.when_hidden(preview_cb);
    this.details_but.addEventListener("click", preview_cb);
}

const container_ids = [
    "install_preview",
    "dialog_container",
    "mapping_preview_container",
    "resource_preview_container"
];

/*
 * Work object is used to communicate between asynchronously executing
 * functions when computing dependencies tree of an item and when fetching
 * files for installation.
 */
async function init_work() {
    const work = {
	waiting: 0,
	is_ok: true,
	db: (await haketilodb.get()),
	result: []
    };

    work.err = function (error, user_message) {
	if (!this.is_ok)
	    return;

	if (error)
	    console.error("Haketilo:", error);
	work.is_ok = false;
	work.reject_cb(user_message);
    }

    return [work,
	    new Promise((...cbs) => [work.resolve_cb, work.reject_cb] = cbs)];
}

function InstallView(tab_id, on_view_show, on_view_hide) {
    Showable.call(this, on_view_show, on_view_hide);

    Object.assign(this, clone_template("install_view"));

    const show_container = name => {
	for (const cid of container_ids) {
	    if (cid !== name)
		this[cid].classList.add("hide");
	}
	this[name].classList.remove("hide");
    }

    this.dialog_ctx = dialog.make(() => show_container("dialog_container"),
				  () => show_container("install_preview"));
    this.dialog_container.prepend(this.dialog_ctx.main_div);

    /* Make a link to view a file from the repository. */
    const make_file_link = (preview_ctx, file_ref) => {
	const a = document.createElement("a");
	a.href = `${this.repo_url}file/sha256/${file_ref.sha256}`;
	a.innerText = file_ref.file;

	return a;
    }

    this.previews_ctx = {};

    this.preview_item = item_def => {
	if (!this.shown)
	    return;

	const fun = ip[`${item_def.type}_preview`];
	const preview_ctx = fun(item_def, this.previews_ctx[item_def.type],
				make_file_link);
	this.previews_ctx[item_def.type] = preview_ctx;

	const container_name = `${item_def.type}_preview_container`;
	show_container(container_name);
	this[container_name].prepend(preview_ctx.main_div);
    }

    let back_cb = () => show_container("install_preview");
    back_cb = this.dialog_ctx.when_hidden(back_cb);
    for (const type of ["resource", "mapping"])
	this[`${type}_back_but`].addEventListener("click", back_cb);

    const process_item = async (work, item_type, id, ver) => {
	if (!work.is_ok || work.processed_by_type[item_type].has(id))
	    return;

	work.processed_by_type[item_type].add(id);
	work.waiting++;

	const url = ver ?
	      `${this.repo_url}${item_type}/${id}/${ver.join(".")}` :
	      `${this.repo_url}${item_type}/${id}.json`;


	try {
	    var response = await indirect_fetch(tab_id, url);
	} catch(e) {
	    return work.err(e, "Failure to communicate with repository :(");
	}

	if (!work.is_ok)
	    return;

	if (!response.ok) {
	    return work.err(null,
			    `Repository sent HTTP code ${response.status} :(`);
	}

	try {
	    var json = await response.json();
	} catch(e) {
	    return work.err(e, "Repository's response is not valid JSON :(");
	}

	if (!work.is_ok)
	    return;

	const captype = item_type[0].toUpperCase() + item_type.substring(1);

	const nonconforming_format_error_msg =
	      `${captype} ${item_id_string(id, ver)} was served using a nonconforming response format.`;

	try {
	    const parsed = parse_schema_uri(json.$schema);
	    var major_schema_version = parsed.major;

	    if (!["1", "2"].includes(major_schema_version)) {
		const msg = `${captype} ${item_id_string(id, ver)} was served using unsupported Hydrilla API version. You might need to update Haketilo.`;
		return work.err(null, msg);
	    }
	} catch(e) {
	    return work.err(e, nonconforming_format_error_msg);
	}

	const schema_name = `api_${item_type}_description-${major_schema_version}.schema.json`;

	const schema = haketilo_schemas[schema_name];
	const result = haketilo_validator.validate(json, schema);
	if (result.errors.length > 0)
	    return work.err(result.errors, nonconforming_format_error_msg);

	const scripts = item_type === "resource" && json.scripts;
	const files = json.source_copyright.concat(scripts || []);

	if (item_type === "mapping") {
	    for (const res_ref of Object.values(json.payloads || {}))
		process_item(work, "resource", res_ref.identifier);
	} else {
	    for (const res_ref of (json.dependencies || []))
		process_item(work, "resource", res_ref.identifier);
	}

	if (major_schema_version >= 2) {
	    for (const map_ref of (json.required_mappings || []))
		process_item(work, "mapping", map_ref.identifier);
	}

	/*
	 * At this point we already have JSON definition of the item and we
	 * triggered processing of its dependencies. We now have to verify if
	 * the same or newer version of the item is already present in the
	 * database and if so - omit this item.
	 */
	const transaction = work.db.transaction(item_type);
	try {
	    var db_def = await haketilodb.idb_get(transaction, item_type, id);
	    if (!work.is_ok)
		return;
	} catch(e) {
	    const msg = "Error accessing Haketilo's internal database :(";
	    return work.err(e, msg);
	}
	if (!db_def || db_def.version < json.version)
	    work.result.push({def: json, db_def});

	if (--work.waiting === 0)
	    work.resolve_cb(work.result);
    }

    async function compute_deps(item_type, item_id, item_ver) {
	const [work, work_prom] = await init_work();
	work.processed_by_type = {"mapping" : new Set(), "resource": new Set()};

	process_item(work, item_type, item_id, item_ver);

	const items = await work_prom;
	items.sort((i1, i2) => compare_items(i1.def, i2.def));
	return items;
    }

    const show_super = this.show;
    this.show = async (repo_url, item_type, item_id, item_ver) => {
	if (!show_super())
	    return;

	this.repo_url = repo_url;

	dialog.loader(this.dialog_ctx, "Fetching data from repository...");

	try {
	    var items = await compute_deps(item_type, item_id, item_ver);
	} catch(e) {
	    var dialog_prom = dialog.error(this.dialog_ctx, e);
	}

	if (!dialog_prom && items.length === 0) {
	    const msg = "Nothing to do - packages already installed.";
	    var dialog_prom = dialog.info(this.dialog_ctx, msg);
	}

	if (dialog_prom) {
	    dialog.close(this.dialog_ctx);

	    await dialog_prom;

	    this.hide();
	    return;
	}

	this.item_entries = items.map(i => new ItemEntry(this, i));
	this.to_install_list.append(...this.item_entries.map(ie => ie.main_li));

	dialog.close(this.dialog_ctx);
    }

    const process_file = async (work, sha256) => {
	if (!work.is_ok)
	    return;

	work.waiting++;

	try {
	    var file_uses = await haketilodb.idb_get(work.file_uses_transaction,
						     "file_uses", sha256);
	    if (!work.is_ok)
		return;
	} catch(e) {
	    const msg = "Error accessing Haketilo's internal database :(";
	    return work.err(e, msg);
	}

	if (!file_uses) {
	    const url = `${this.repo_url}file/sha256/${sha256}`;

	    try {
		var response = await fetch(url);
		if (!work.is_ok)
		    return;
	    } catch(e) {
		const msg = "Failure to communicate with repository :(";
		return work.err(e, msg);
	    }

	    if (!response.ok) {
		const msg = `Repository sent HTTP code ${response.status} :(`;
		return work.err(null, msg);
	    }

	    const text = await response.text();
	    if (!work.is_ok)
		return;

	    const digest = await compute_sha256(text);
	    if (!work.is_ok)
		return;
	    if (digest !== sha256) {
		const msg = `${url} served a file with different SHA256 cryptographic sum :(`;
		return work.err(null, msg);
	    }

	    work.result.push([sha256, text]);
	}

	if (--work.waiting === 0)
	    work.resolve_cb(work.result);
    }

    const get_missing_files = async item_defs => {
	const [work, work_prom] = await init_work();
	work.file_uses_transaction = work.db.transaction("file_uses");

	const processed_files = new Set();

	for (const item_def of item_defs) {
	    for (const file of get_files(item_def)) {
		if (!processed_files.has(file.sha256)) {
		    processed_files.add(file.sha256);
		    process_file(work, file.sha256);
		}
	    }
	}

	return processed_files.size > 0 ? work_prom : [];
    }

    const perform_install = async () => {
	if (!this.show || !this.item_entries)
	    return;

	dialog.loader(this.dialog_ctx, "Installing...");

	const item_defs = this.item_entries.map(ie => ie.item_def);

	try {
	    var files = (await get_missing_files(item_defs))
		.reduce((ac, [h, txt]) => Object.assign(ac, {[h]: txt}), {});
	} catch(e) {
	    var dialog_prom = dialog.error(this.dialog_ctx, e);
	}

	if (files !== undefined) {
	    const data = {file: {sha256: files}};

	    for (const type of ["resource", "mapping"]) {
		const set = {};

		for (const def of item_defs.filter(def => def.type === type))
		    set[def.identifier] = {[version_string(def.version)]: def};

		data[type] = set;
	    }

	    try {
		await haketilodb.save_items(data);
	    } catch(e) {
		console.error("Haketilo:", e);
		const msg = "Error writing to Haketilo's internal database :(";
		var dialog_prom = dialog.error(this.dialog_ctx, msg);
	    }
	}

	if (!dialog_prom) {
	    const msg = "Successfully installed!";
	    var dialog_prom = dialog.info(this.dialog_ctx, msg);
	}

	dialog.close(this.dialog_ctx);

	await dialog_prom;

	this.hide();
    }

    const hide_super = this.hide;
    this.hide = () => {
	if (!hide_super())
	    return;

	delete this.item_entries;
	[...this.to_install_list.children].forEach(n => n.remove());
    }

    const hide_cb = this.dialog_ctx.when_hidden(this.hide);
    this.cancel_but.addEventListener("click", hide_cb);

    const install_cb = this.dialog_ctx.when_hidden(perform_install);
    this.install_but.addEventListener("click", install_cb);
}
#EXPORT InstallView