import "./history-view.scss";

import type { IconName, WorkspaceLeaf } from "obsidian";
import { ItemView, setIcon } from "obsidian";
import { intlFormatDistance } from "date-fns";
import type { HistoryEntry, SyncClient } from "sync-client";
import { SyncType } from "sync-client";

export class HistoryView extends ItemView {
    public static readonly TYPE = "history-view";
    public static readonly ICON = "square-stack";
    private timer: NodeJS.Timeout | null = null;

    private historyContainer: HTMLElement | undefined;
    private readonly historyEntryToElement = new Map<
        HistoryEntry,
        HTMLElement
    >();

    public constructor(
        private readonly client: SyncClient,
        leaf: WorkspaceLeaf
    ) {
        super(leaf);
        this.icon = HistoryView.ICON;

        this.client.onSyncHistoryUpdated.add(async () =>
            this.updateView().catch((error: unknown) => {
                this.client.logger.error(
                    `Failed to update history view: ${error}`
                );
            })
        );
    }

    private static getSyncTypeIcon(type: SyncType | undefined): IconName {
        switch (type) {
            case SyncType.CREATE:
                return "file-plus";
            case SyncType.DELETE:
                return "trash-2";
            case SyncType.UPDATE:
                return "file-pen-line";
            case SyncType.MOVE:
                return "move-right";
            case SyncType.SKIPPED:
                return "circle-slash";
            case undefined:
            default:
                return "";
        }
    }

    private static renderSyncItemTitle(
        element: HTMLElement,
        entry: HistoryEntry
    ): void {
        const syncTypeIcon = HistoryView.getSyncTypeIcon(entry.details.type);
        if (syncTypeIcon) {
            setIcon(element.createDiv(), syncTypeIcon);
        }

        let fileName = entry.details.relativePath.split("/").pop() ?? "";
        fileName = fileName.replace(/\.md$/, "");

        element.createEl("span", {
            text:
                entry.details.type === SyncType.SKIPPED
                    ? `Skipped: ${fileName}`
                    : fileName
        });
    }

    private static updateTimeSince(
        element: HTMLElement,
        entry: HistoryEntry
    ): void {
        const timestampElement = element.querySelector(
            ".history-card-timestamp"
        );

        if (timestampElement != null) {
            timestampElement.textContent =
                HistoryView.getTimestampAndAuthor(entry);
        }
    }

    private static getTimestampAndAuthor(entry: HistoryEntry): string {
        let content = intlFormatDistance(entry.timestamp, new Date());
        if ("author" in entry && entry.author !== undefined) {
            content += ` by ${entry.author}`;
        }
        return content;
    }

    public getViewType(): string {
        return HistoryView.TYPE;
    }

    public getDisplayText(): string {
        return "VaultLink history";
    }

    public async onOpen(): Promise<void> {
        const container = this.containerEl.children[1];
        container.createEl("h4", { text: "VaultLink history" });

        this.historyContainer = container.createDiv({ cls: "logs-container" });

        await this.updateView();
        this.clearTimer();
        this.timer = setInterval(
            () =>
                void this.updateView().catch((error: unknown) => {
                    this.client.logger.error(
                        `Failed to update history view: ${error}`
                    );
                }),
            1000
        );
    }

    public async onClose(): Promise<void> {
        this.clearTimer();
    }

    private clearTimer(): void {
        if (this.timer) {
            clearInterval(this.timer);
            this.timer = null;
        }
    }

    private async updateView(): Promise<void> {
        const container = this.historyContainer;
        if (container === undefined) {
            return;
        }

        // entries are newest first, but we prepend new ones
        const entries = this.client.getHistoryEntries().toReversed();

        if (this.historyEntryToElement.size === 0 && entries.length > 0) {
            // Clear the "No update has happened yet" message
            container.empty();
        }

        entries.forEach((entry) => {
            const element = this.historyEntryToElement.get(entry);
            if (element !== undefined) {
                HistoryView.updateTimeSince(element, entry);
                return;
            }

            const newElement = this.createHistoryCard(container, entry);
            container.prepend(newElement);
            this.historyEntryToElement.set(entry, newElement);
        });

        const newEntries = new Set(entries);
        for (const [entry, element] of this.historyEntryToElement) {
            if (!newEntries.has(entry)) {
                element.remove();
                this.historyEntryToElement.delete(entry);
            }
        }

        if (entries.length === 0) {
            container.empty();
            container.createEl("p", {
                text: "No update has happened yet."
            });
        }
    }

    private createHistoryCard(
        container: HTMLElement,
        entry: HistoryEntry
    ): HTMLElement {
        return container.createDiv(
            {
                cls: ["history-card", entry.status.toLocaleLowerCase()]
            },
            (card) => {
                if (
                    this.app.vault.getFileByPath(entry.details.relativePath) !=
                    null
                ) {
                    card.addEventListener("click", () => {
                        this.app.workspace
                            .openLinkText(
                                entry.details.relativePath,
                                entry.details.relativePath,
                                false
                            )
                            .catch((error: unknown) => {
                                this.client.logger.error(
                                    `Failed to open link for ${entry.details.relativePath}: ${error}`
                                );
                            });
                    });

                    card.addClass("clickable");
                }

                card.createDiv(
                    {
                        cls: "history-card-header"
                    },
                    (header) => {
                        header.createEl(
                            "h5",
                            {
                                cls: "history-card-title"
                            },
                            (title) => {
                                HistoryView.renderSyncItemTitle(title, entry);
                            }
                        );

                        header.createSpan({
                            text: HistoryView.getTimestampAndAuthor(entry),
                            cls: "history-card-timestamp"
                        });
                    }
                );

                const body =
                    entry.details.type === SyncType.MOVE
                        ? `${entry.message}. Moved from '${entry.details.movedFrom}' to '${entry.details.relativePath}'`
                        : `${entry.message}.`;

                card.createEl("p", {
                    text: body,
                    cls: "history-card-message"
                });
            }
        );
    }
}