// The Diffusion view (oxygenhub-vscode#5, oxygenhub docs/diffusion.md): for
// each repository, the subrepos it takes from and the repositories it
// diffuses to, each with the hub's pill in words and its open bump.

import * as vscode from "vscode";
import type * as api from "./hubapi";
import { HubAuth } from "./auth";
import { hubUrl } from "./hub";
import type { HubRepo } from "./proposals";
import { look, pinDescription, pinLabel, pinTooltip, tone } from "./diffusionview";

type Side = "takes" | "gives";

type Node =
  | { kind: "repo"; repo: HubRepo }
  | { kind: "side"; repo: HubRepo; side: Side; pins: api.DiffusionPin[] }
  | { kind: "pin"; repo: HubRepo; side: Side; pin: api.DiffusionPin }
  | { kind: "none"; repo: HubRepo };

export type DiffusionPinNode = Extract<Node, { kind: "pin" }>;

export class DiffusionProvider implements vscode.TreeDataProvider<Node> {
  private readonly emitter = new vscode.EventEmitter<void>();
  readonly onDidChangeTreeData = this.emitter.event;

  constructor(
    private readonly repos: () => Promise<HubRepo[]>,
    private readonly auth: HubAuth,
  ) {}

  refresh(): void {
    this.emitter.fire();
  }

  getTreeItem(node: Node): vscode.TreeItem {
    switch (node.kind) {
      case "repo": {
        const item = new vscode.TreeItem(`${node.repo.owner}/${node.repo.name}`, vscode.TreeItemCollapsibleState.Expanded);
        item.iconPath = new vscode.ThemeIcon("repo");
        item.contextValue = "diffusionRepo";
        return item;
      }
      case "side": {
        const item = new vscode.TreeItem(node.side === "takes" ? "Takes from" : "Diffuses to", vscode.TreeItemCollapsibleState.Expanded);
        item.description = String(node.pins.length);
        item.iconPath = new vscode.ThemeIcon(node.side === "takes" ? "arrow-down" : "arrow-up");
        return item;
      }
      case "pin": {
        const t = tone(node.pin);
        const l = look(t);
        const item = new vscode.TreeItem(pinLabel(node.pin, node.side), vscode.TreeItemCollapsibleState.None);
        item.description = pinDescription(node.pin);
        item.iconPath = new vscode.ThemeIcon(l.icon, new vscode.ThemeColor(l.color));
        item.tooltip = new vscode.MarkdownString(pinTooltip(node.pin));
        item.contextValue = node.pin.bump !== null && node.pin.bump !== undefined ? "diffusionPinBump" : "diffusionPin";
        item.command = { title: "Open", command: "oxygenhub.openDiffusionPin", arguments: [node] };
        return item;
      }
      case "none": {
        const item = new vscode.TreeItem("Neither pins nor is pinned by a repository on the hub", vscode.TreeItemCollapsibleState.None);
        item.iconPath = new vscode.ThemeIcon("info");
        return item;
      }
    }
  }

  async getChildren(node?: Node): Promise<Node[]> {
    if (!node) {
      return (await this.repos()).map((repo) => ({ kind: "repo", repo }));
    }
    if (node.kind === "repo") {
      try {
        const d = await this.auth.clientFor(node.repo.base).diffusion(node.repo.owner, node.repo.name);
        const out: Node[] = [];
        if (d.takes_from.length > 0) {
          out.push({ kind: "side", repo: node.repo, side: "takes", pins: d.takes_from });
        }
        if (d.diffuses_to.length > 0) {
          out.push({ kind: "side", repo: node.repo, side: "gives", pins: d.diffuses_to });
        }
        return out.length > 0 ? out : [{ kind: "none", repo: node.repo }];
      } catch (e) {
        void vscode.window.showWarningMessage(`OxygenHub: ${(e as Error).message}`);
        return [];
      }
    }
    if (node.kind === "side") {
      return node.pins.map((pin) => ({ kind: "pin", repo: node.repo, side: node.side, pin }));
    }
    return [];
  }
}

/** Where a row leads on the hub: its open bump, else the other repository. */
export function pinUrl(node: DiffusionPinNode): string {
  const [owner, name] = (node.side === "takes" ? node.pin.upstream : node.pin.consumer).split("/");
  const [cOwner, cName] = node.pin.consumer.split("/");
  if (node.pin.bump !== null && node.pin.bump !== undefined) {
    return hubUrl(node.repo.base, cOwner, cName, { kind: "proposal", number: node.pin.bump });
  }
  return hubUrl(node.repo.base, owner, name, { kind: "repository" });
}

/** The repository's Diffusion tab on the hub. */
export function diffusionTab(repo: HubRepo): string {
  return hubUrl(repo.base, repo.owner, repo.name, { kind: "diffusion" });
}