/**
 * Unit tests for the layered graph layout: parent centering, depth rows, the
 * sibling-band WRAP that keeps a narrow sidebar readable (and the row
 * reservation that stops a wrapped band from landing on a sibling's
 * children), the live-line height, and the width-aware solver.
 */
import { describe, expect, it } from 'vitest'
import {
  GRAPH_GAP_Y,
  GRAPH_LIVE_H,
  GRAPH_NODE_H,
  GRAPH_NODE_W,
  GRAPH_PAD,
  GRAPH_ROW_STRIDE,
  bandColsFor,
  layoutTasksGraph,
  layoutTasksGraphForWidth,
} from '../src/client/tasks-graph-layout.ts'
import type { TasksAgentNode, TasksNode } from '../src/client/tasks-model.ts'

/** An agent node. */
function agent(id: string, parentId?: string, live = false): TasksAgentNode {
  return {
    kind: 'agent', id, ...(parentId === undefined ? {} : { parentId }),
    label: id, state: 'running', activity: 'running', current: false,
    ...(live ? { live: { text: 'x' } } : {}),
  }
}

/** The row index of one laid-out node. */
function layoutRow(layout: ReturnType<typeof layoutTasksGraph>, id: string): number {
  const box = layout.boxes.get(id)
  if (box === undefined) throw new Error(`no box for ${id}`)
  return (box.y - GRAPH_PAD) / GRAPH_ROW_STRIDE
}

describe('layoutTasksGraph', () => {
  it('places the root on row 0 and children one row below', () => {
    const nodes: TasksNode[] = [agent('root'), agent('a', 'root'), agent('b', 'root')]
    const layout = layoutTasksGraph(nodes)
    // A running agent reserves the live-line row (its "thinking" fallback).
    expect(layout.boxes.get('root')).toMatchObject({ y: GRAPH_PAD, h: GRAPH_NODE_H + GRAPH_LIVE_H })
    expect(layout.boxes.get('a')?.y).toBe(GRAPH_PAD + GRAPH_ROW_STRIDE)
    expect(layout.boxes.get('b')?.y).toBe(GRAPH_PAD + GRAPH_ROW_STRIDE)
  })

  it('centers a parent over its children band', () => {
    const nodes: TasksNode[] = [agent('root'), agent('a', 'root'), agent('b', 'root')]
    const layout = layoutTasksGraph(nodes)
    const a = layout.boxes.get('a')
    const b = layout.boxes.get('b')
    const root = layout.boxes.get('root')
    expect(a).toBeDefined(); expect(b).toBeDefined(); expect(root).toBeDefined()
    const bandCenter = (a!.x + b!.x + GRAPH_NODE_W) / 2
    expect(root!.x + GRAPH_NODE_W / 2).toBeCloseTo(bandCenter, 5)
  })

  it('grows live rows and widens the canvas for deep/wide forests', () => {
    const nodes: TasksNode[] = [
      agent('root'), agent('a', 'root', true),
      agent('a1', 'a'), agent('a2', 'a'), agent('a3', 'a'),
    ]
    const layout = layoutTasksGraph(nodes)
    expect(layout.boxes.get('a')?.h).toBe(GRAPH_NODE_H + GRAPH_LIVE_H)
    expect(layout.width).toBeGreaterThan(3 * GRAPH_NODE_W)
    expect(layout.height).toBeGreaterThan(2 * (GRAPH_NODE_H + GRAPH_GAP_Y))
  })

  it('gives every node a box even with a defensive orphan', () => {
    const nodes: TasksNode[] = [agent('root'), agent('ghost', 'missing')]
    const layout = layoutTasksGraph(nodes)
    expect(layout.boxes.get('root')).toBeDefined()
    expect(layout.boxes.get('ghost')).toBeDefined()
  })

  it('wraps a wide sibling band into rows of maxBandCols', () => {
    const nodes: TasksNode[] = [agent('root')]
    for (let index = 0; index < 5; index += 1) nodes.push(agent(`c${index}`, 'root'))
    const layout = layoutTasksGraph(nodes, { maxBandCols: 2 })
    // Three wrapped rows of 2/2/1, never five on one line.
    expect([layoutRow(layout, 'c0'), layoutRow(layout, 'c1')]).toEqual([1, 1])
    expect([layoutRow(layout, 'c2'), layoutRow(layout, 'c3')]).toEqual([2, 2])
    expect(layoutRow(layout, 'c4')).toBe(3)
    // The canvas stays as narrow as one wrapped band.
    expect(layout.width).toBeLessThanOrEqual(2 * GRAPH_NODE_W + 28 + 2 * GRAPH_PAD)
  })

  it('never lets a wrapped band land on a sibling subtree row', () => {
    // root → [a (with a child), b, c, d] wrapped at 2 columns: the second
    // band must start BELOW a's child, not on the same row as it.
    const nodes: TasksNode[] = [
      agent('root'), agent('a', 'root'), agent('b', 'root'),
      agent('c', 'root'), agent('d', 'root'), agent('a1', 'a'),
    ]
    const layout = layoutTasksGraph(nodes, { maxBandCols: 2 })
    expect(layoutRow(layout, 'c')).toBeGreaterThan(layoutRow(layout, 'a1'))
    expect(layoutRow(layout, 'd')).toBe(layoutRow(layout, 'c'))
  })
})

describe('bandColsFor / layoutTasksGraphForWidth', () => {
  it('derives the column count from the container width', () => {
    expect(bandColsFor(360)).toBe(2)
    expect(bandColsFor(720)).toBe(4)
    expect(bandColsFor(120)).toBe(1)
  })

  it('prefers a flat band when the container is wide', () => {
    const nodes: TasksNode[] = [agent('root')]
    for (let index = 0; index < 4; index += 1) nodes.push(agent(`c${index}`, 'root'))
    const wide = layoutTasksGraphForWidth(nodes, 720)
    expect(['c0', 'c1', 'c2', 'c3'].map(id => layoutRow(wide, id))).toEqual([1, 1, 1, 1])
  })

  it('wraps instead of overflowing wildly when the container is narrow', () => {
    const nodes: TasksNode[] = [agent('root')]
    for (let index = 0; index < 6; index += 1) nodes.push(agent(`c${index}`, 'root'))
    const narrow = layoutTasksGraphForWidth(nodes, 360)
    // Never wider than the tolerant budget (a small pan is allowed, a 3x
    // overflow is not), and never a one-child-per-row ladder.
    expect(narrow.width).toBeLessThanOrEqual(((360 - 24) / 0.78) * 1.2)
    expect(layoutRow(narrow, 'c1')).toBe(layoutRow(narrow, 'c0'))
  })
})