import { describe, expect, it } from "vitest";

import {
  MAX_ROWS_PER_COLUMN,
  computeLayout,
} from "@/components/admin/tech-tree/layout";
import {
  COLUMN_STEP,
  NODE_WIDTH,
  ROW_STEP,
  type TreeCategory,
  type TreeTech,
} from "@/components/admin/tech-tree/types";

const tech = (over: Partial<TreeTech> & { id: number }): TreeTech => ({
  name: `Tech ${over.id}`,
  type: "upgrade",
  approvalStatus: "in_progress",
  summary: "",
  categoryId: null,
  prereqAnd: [],
  prereqOr: [],
  resourceCosts: [],
  treePosition: null,
  ...over,
});

const cat = (id: number, name: string, position: number): TreeCategory => ({
  id,
  name,
  position,
  color: null,
});

describe("tech tree layout (pure)", () => {
  it("wraps a long uncategorized column into multiple physical columns", () => {
    const techs = Array.from({ length: 25 }, (_, i) => tech({ id: i + 1 }));
    const layout = computeLayout(techs, []);

    const xs = [...new Set(layout.nodes.map((n) => n.x))].sort((a, b) => a - b);
    expect(xs).toEqual([0, COLUMN_STEP, COLUMN_STEP * 2]);
    expect(layout.columns).toBe(3);

    // First column holds MAX_ROWS_PER_COLUMN nodes, rows 0..N-1.
    const firstColumnRows = layout.nodes.filter((n) => n.x === 0).map((n) => n.y / ROW_STEP);
    expect(firstColumnRows.sort((a, b) => a - b)).toEqual(
      Array.from({ length: MAX_ROWS_PER_COLUMN }, (_, i) => i),
    );
    // The final column holds the remainder.
    const lastColumnCount = layout.nodes.filter((n) => n.x === COLUMN_STEP * 2).length;
    expect(lastColumnCount).toBe(25 - MAX_ROWS_PER_COLUMN * 2);
  });

  it("orders category columns by explicit position, then name", () => {
    const categories = [cat(10, "Tier 2", 2), cat(11, "Tier 1", 1), cat(12, "Alpha", 2)];
    const techs = [
      tech({ id: 1, categoryId: 10 }),
      tech({ id: 2, categoryId: 11 }),
      tech({ id: 3, categoryId: 12 }),
    ];
    const layout = computeLayout(techs, categories);
    const xOf = (id: number) => layout.nodes.find((n) => n.techId === id)!.x;

    // Tier 1 (position 1) is leftmost.
    expect(xOf(2)).toBe(0);
    // Position 2 ties break alphabetically: "Alpha" before "Tier 2".
    expect(xOf(3)).toBe(COLUMN_STEP);
    expect(xOf(1)).toBe(COLUMN_STEP * 2);
  });

  it("places uncategorized techs in a trailing zone after all categories", () => {
    const categories = [cat(1, "Tier 1", 1), cat(2, "Tier 2", 2)];
    const techs = [
      tech({ id: 1, categoryId: 1 }),
      tech({ id: 2, categoryId: 2 }),
      tech({ id: 3 }),
    ];
    const layout = computeLayout(techs, categories);
    const xOf = (id: number) => layout.nodes.find((n) => n.techId === id)!.x;
    expect(xOf(3)).toBe(COLUMN_STEP * 2); // after both category columns
  });

  it("places a dependent one column right of its parent, at the parent's row", () => {
    const techs = [tech({ id: 1 }), tech({ id: 2, prereqAnd: [1] })];
    const layout = computeLayout(techs, []);
    const parent = layout.nodes.find((n) => n.techId === 1)!;
    const child = layout.nodes.find((n) => n.techId === 2)!;
    expect(child.column).toBe(parent.column + 1);
    expect(child.row).toBe(parent.row);
    // Short, local edge: exactly one column apart.
    expect(child.x - parent.x).toBe(COLUMN_STEP);
  });

  it("keeps the chain propagating rightwards for grandchildren", () => {
    const techs = [
      tech({ id: 1 }),
      tech({ id: 2, prereqAnd: [1] }),
      tech({ id: 3, prereqAnd: [2] }),
    ];
    const layout = computeLayout(techs, []);
    const col = (id: number) => layout.nodes.find((n) => n.techId === id)!.column;
    expect(col(2)).toBe(col(1) + 1);
    expect(col(3)).toBe(col(2) + 1);
  });

  it("links stay beside their parent even when the root grid fills its columns", () => {
    // 25 roots fill three 10-row columns; a dependent of the FIRST root must
    // still land immediately to its right, not after the whole grid.
    const roots = Array.from({ length: 25 }, (_, i) => tech({ id: i + 1 }));
    const techs = [...roots, tech({ id: 100, prereqAnd: [1] })];
    const layout = computeLayout(techs, []);
    const parent = layout.nodes.find((n) => n.techId === 1)!;
    const child = layout.nodes.find((n) => n.techId === 100)!;
    // Adjacent column, and right next to the parent vertically (it may grow
    // upwards into a free slot rather than being pushed to a distant column).
    expect(child.column).toBe(parent.column + 1);
    expect(Math.abs(child.row - parent.row)).toBeLessThanOrEqual(1);
  });

  it("keeps the catalog grid stable when a root becomes a dependent", () => {
    const roots = ["Alpha", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot"].map((name, i) =>
      tech({ id: i + 1, name }),
    );
    const before = computeLayout(roots, []);
    const posBefore = (layout: ReturnType<typeof computeLayout>, id: number) =>
      layout.nodes.find((n) => n.techId === id)!;

    // Foxtrot (id 6) becomes Charlie's prerequisite: Charlie (id 3) leaves the
    // catalog and becomes a dependent.
    const after = computeLayout(
      roots.map((t) => (t.id === 3 ? { ...t, prereqAnd: [6] } : t)),
      [],
    );

    // Every other root keeps its exact slot: no re-shuffling on connect.
    for (const id of [1, 2, 4, 5, 6]) {
      expect(after.nodes.find((n) => n.techId === id)!.x).toBe(posBefore(before, id).x);
      expect(after.nodes.find((n) => n.techId === id)!.y).toBe(posBefore(before, id).y);
    }
    // Charlie's catalog slot is now empty, and it sits right of its prerequisite.
    const foxtrot = after.nodes.find((n) => n.techId === 6)!;
    const charlie = after.nodes.find((n) => n.techId === 3)!;
    expect(charlie.column).toBe(foxtrot.column + 1);
    expect(charlie.row).toBe(foxtrot.row);
  });

  it("keeps a pinned dependent exactly where it was placed", () => {
    const techs = [
      tech({ id: 1 }),
      tech({ id: 2, prereqAnd: [1], treePosition: { x: 1234, y: 567 } }),
    ];
    const layout = computeLayout(techs, []);
    const pinned = layout.nodes.find((n) => n.techId === 2)!;
    expect(pinned.x).toBe(1234);
    expect(pinned.y).toBe(567);
  });

  it("uses the average parent row for multi-parent dependents", () => {
    const techs = [
      tech({ id: 1 }),
      tech({ id: 2 }),
      tech({ id: 3 }),
      tech({ id: 4 }),
      tech({ id: 5 }),
      tech({ id: 6, prereqAnd: [1, 5] }),
    ];
    const layout = computeLayout(techs, []);
    const row = (id: number) => layout.nodes.find((n) => n.techId === id)!.row;
    const child = layout.nodes.find((n) => n.techId === 6)!;
    expect(child.row).toBe(Math.round((row(1) + row(5)) / 2));
    expect(child.column).toBe(1);
  });

  it("stacks siblings without overlapping them", () => {
    const techs = [
      tech({ id: 1 }),
      tech({ id: 2, prereqAnd: [1] }),
      tech({ id: 3, prereqAnd: [1] }),
      tech({ id: 4, prereqAnd: [1] }),
    ];
    const layout = computeLayout(techs, []);
    const siblings = layout.nodes.filter((n) => [2, 3, 4].includes(n.techId));
    expect(new Set(siblings.map((n) => n.column)).size).toBe(1);
    expect(new Set(siblings.map((n) => n.row)).size).toBe(3);
  });

  it("honors manual treePosition overrides and grows the band to contain them", () => {
    const categories = [cat(1, "Tier 1", 1)];
    const techs = [
      tech({ id: 1, categoryId: 1 }),
      tech({ id: 2, categoryId: 1, treePosition: { x: 900, y: 400 } }),
    ];
    const layout = computeLayout(techs, categories);

    const manual = layout.nodes.find((n) => n.techId === 2)!;
    expect(manual.x).toBe(900);
    expect(manual.y).toBe(400);

    const band = layout.bands.find((b) => b.key === "cat-1")!;
    // Band spans from the auto-positioned node to the dragged node.
    expect(band.x + band.width).toBeGreaterThanOrEqual(900 + NODE_WIDTH);
  });

  it("flags a prerequisite that sits in a later column", () => {
    const categories = [cat(1, "Tier 1", 1), cat(2, "Tier 2", 2)];
    const techs = [
      tech({ id: 1, categoryId: 1, prereqAnd: [2] }), // depends on a Tier 2 tech
      tech({ id: 2, categoryId: 2 }),
    ];
    const layout = computeLayout(techs, categories);
    expect(layout.warnings.map((w) => w.techId)).toContain(1);
  });

  it("does not flag forward-pointing prerequisites", () => {
    const categories = [cat(1, "Tier 1", 1), cat(2, "Tier 2", 2)];
    const techs = [
      tech({ id: 1, categoryId: 1 }),
      tech({ id: 2, categoryId: 2, prereqAnd: [1] }),
    ];
    const layout = computeLayout(techs, categories);
    expect(layout.warnings).toEqual([]);
  });

  it("survives prerequisite cycles", () => {
    const techs = [
      tech({ id: 1, prereqAnd: [2] }),
      tech({ id: 2, prereqAnd: [1] }),
    ];
    const layout = computeLayout(techs, []);
    expect(layout.nodes).toHaveLength(2);
  });

  it("omits bands for categories with no members", () => {
    const categories = [cat(1, "Tier 1", 1), cat(2, "Empty Tier", 2)];
    const techs = [tech({ id: 1, categoryId: 1 })];
    const layout = computeLayout(techs, categories);
    expect(layout.bands.map((b) => b.key)).toEqual(["cat-1"]);
  });

  it("ignores dangling category references by treating them as uncategorized", () => {
    const techs = [tech({ id: 1, categoryId: 999 })];
    const layout = computeLayout(techs, [cat(1, "Tier 1", 1)]);
    expect(layout.bands.map((b) => b.key)).toEqual(["uncategorized"]);
  });
});