import std.array;
import std.algorithm;
import std.experimental.logger;
import std.file;
import std.stdio;

import vibe.d;

import app;
import page;

/**
 * Loads pages into memory and sets up a "watcher" to watch a directory for file changes.
 */
void initPages(T, string sortPred)(ref T[string] array, ref T*[] sortedRange, const string directory) {

	bool addPage(string path) {
		try {
			T newPage = new T(path);
			logf("Added %s", newPage.slug);
			array[newPage.slug] = newPage;
			return true;
		} catch (page.ArticleParseException e) {
			logf("Could not parse %s", path);
			return false;
		}
	}

	// Initial scan
	void scan(NativePath path, int level = 0) {
		logf("Scanning %s", path.toString());
		foreach(file; iterateDirectory(path)) {
			if (file.isDirectory) {
				scan(path ~ file.name, level + 1);
			} else {
				addPage((path ~ file.name).toString());
			}
		}
	}

	void sortThings() {
		sortedRange = sort!(sortPred)(array.values)
			.filter!(x => !x.isHidden)
			.map!"&a".array;
		logf("sorted: %s", sortedRange);
	}

	if (!existsFile(getWorkingDirectory() ~ directory)) {
		createDirectory(getWorkingDirectory() ~ directory);
	}
	scan(getWorkingDirectory() ~ directory);
	sortThings();
	
	DirectoryWatcher watcher = watchDirectory(getWorkingDirectory() ~ directory, true);
	//auto watcher = FileWatch((getWorkingDirectory() ~ directory).toString(), true);

	bool shouldStop = false;
	while (!shouldStop) {
		// Try to reduce changes to only one DirectoryChangeType per change
		DirectoryChange[] changes;
		shouldStop = !watcher.readChanges(changes);
		foreach(change; changes) {
			logf("=======[New changes]======");
			string[] changeTypes = ["added", "removed", "modified"];
			logf("Path: %s, type: %s", change.path.toString(), changeTypes[change.type]);
			if (endsWith(change.path.toString(), ".kate-swp")) continue;
			switch (change.type) with (DirectoryChangeType){
				case added:
					try {
						addPage(change.path.toString());
					} catch(Exception e) {
						warningf("Error while updating %s: %s", change.path.toString(), e.msg);
					}
					break;
				case modified:
					T newPage;
					try {
						newPage = new T(change.path.toString());
						log(newPage.slug);
						if (newPage.slug in array) {
							log("Slug not changed");
							array[newPage.slug] = newPage;
						} else {
							log("Slug changed");
							foreach(item; array) {
								if (item.name == change.path.toString()) {
									logf("Removed %s, which is the old slug of %s", newPage.slug, item.slug);
									array.remove(item.slug);
								}
							}
						}
						logf("%s modified: %s", typeid(T).stringof, newPage.slug);
						array[newPage.slug] = newPage;
					} catch(page.ArticleParseException e) {
						warningf("Could not parse %s", change.path.toString());
					} catch (Exception e) {
						warningf("Error while updating %s: %s", change.path.toString(), e.msg);
					}
					break;
				case removed:
					try {
						foreach(item; array.byValue) {
							logf(" - %s", item.name);
							if (item.name == change.path.toString()) {
								logf("Removed %s", item.slug);
								array.remove(item.slug);
							}
						}
					} catch(Exception e) {}
					break;
				default: break;
			}
			log("Current state:");
			//sortedRange = sort!("a."~sortProp~" < b."~sortProp)(array.values);
			sortThings();
			foreach (item; array) {
				logf("%s - %s", item.name, item.slug);
			}
		}
	}
}