import { describe, it, expect, vi } from 'vitest'
import { existsSync, readFileSync } from 'node:fs'
import { join } from 'node:path'
import { SkillTreePanel, SKILL_PANEL_ORIGIN } from '../src/ui/skill-tree-panel.ts'
import { BAKED_UI_MANIFEST } from '../src/ui/baked-ui-meta.ts'
import type { D2FontRenderer } from '../src/ui/font.ts'

describe('Issue #377: Authentic D2 v1.13c Skill Tree Tabs & Skill Points Banner', () => {
  it('manifest contains skillTabs and skillPoints image references', () => {
    expect(BAKED_UI_MANIFEST.images.skillTabs).toBe('/ui/skill-tree-tabs.png')
    expect(BAKED_UI_MANIFEST.images.skillPoints).toBe('/ui/skillpoints.png')

    const tabsPath = join(process.cwd(), 'public', 'ui', 'skill-tree-tabs.png')
    const spPath = join(process.cwd(), 'public', 'ui', 'skillpoints.png')

    expect(existsSync(tabsPath), 'skill-tree-tabs.png must exist in public/ui').toBe(true)
    expect(existsSync(spPath), 'skillpoints.png must exist in public/ui').toBe(true)
  })

  it('skill-tree-tabs.png has authentic 192x432 strip dimensions (3 states x 64x432)', () => {
    const tabsPath = join(process.cwd(), 'public', 'ui', 'skill-tree-tabs.png')
    const buf = readFileSync(tabsPath)
    // PNG width and height at bytes 16..24
    const width = buf.readUInt32BE(16)
    const height = buf.readUInt32BE(20)
    expect(width).toBe(192)
    expect(height).toBe(432)
  })

  it('skillpoints.png has authentic 135x23 dimensions', () => {
    const spPath = join(process.cwd(), 'public', 'ui', 'skillpoints.png')
    const buf = readFileSync(spPath)
    const width = buf.readUInt32BE(16)
    const height = buf.readUInt32BE(20)
    expect(width).toBe(135)
    expect(height).toBe(23)
  })

  it('draws authentic 64x432 tab column slice according to activeTab', () => {
    const panel = new SkillTreePanel()
    panel.visible = true

    const mockCtx = {
      save: vi.fn(),
      restore: vi.fn(),
      drawImage: vi.fn(),
      fillRect: vi.fn(),
      strokeRect: vi.fn(),
      fillStyle: '',
      strokeStyle: '',
      lineWidth: 1,
      globalAlpha: 1,
    } as unknown as CanvasRenderingContext2D

    const mockFont = {
      drawText: vi.fn(),
      measureText: vi.fn(() => 50),
    } as unknown as D2FontRenderer

    const mockTabsImg = {
      complete: true,
      naturalWidth: 192,
      naturalHeight: 432,
    } as unknown as HTMLImageElement

    const mockSpImg = {
      complete: true,
      naturalWidth: 135,
      naturalHeight: 23,
    } as unknown as HTMLImageElement

    // 1. Tab 2 (Cold Spells, Top Tab): slice sx = 0
    panel.activeTab = 2
    panel.draw(mockCtx, {
      borderRightImg: null,
      skillPointsImg: mockSpImg,
      buySellBtnImg: null,
      skillTabsImg: mockTabsImg,
    }, mockFont)

    expect(mockCtx.drawImage).toHaveBeenCalledWith(
      mockTabsImg,
      0, // sx = 0
      0,
      64,
      432,
      SKILL_PANEL_ORIGIN.x + 256,
      SKILL_PANEL_ORIGIN.y,
      64,
      432,
    )

    // 2. Tab 1 (Lightning Spells, Middle Tab): slice sx = 64
    vi.clearAllMocks()
    panel.activeTab = 1
    panel.draw(mockCtx, {
      borderRightImg: null,
      skillPointsImg: mockSpImg,
      buySellBtnImg: null,
      skillTabsImg: mockTabsImg,
    }, mockFont)

    expect(mockCtx.drawImage).toHaveBeenCalledWith(
      mockTabsImg,
      64, // sx = 64
      0,
      64,
      432,
      SKILL_PANEL_ORIGIN.x + 256,
      SKILL_PANEL_ORIGIN.y,
      64,
      432,
    )

    // 3. Tab 0 (Fire Spells, Bottom Tab): slice sx = 128
    vi.clearAllMocks()
    panel.activeTab = 0
    panel.draw(mockCtx, {
      borderRightImg: null,
      skillPointsImg: mockSpImg,
      buySellBtnImg: null,
      skillTabsImg: mockTabsImg,
    }, mockFont)

    expect(mockCtx.drawImage).toHaveBeenCalledWith(
      mockTabsImg,
      128, // sx = 128
      0,
      64,
      432,
      SKILL_PANEL_ORIGIN.x + 256,
      SKILL_PANEL_ORIGIN.y,
      64,
      432,
    )
  })

  it('draws authentic skillpoints.png banner when unspentSkillPoints > 0', () => {
    const panel = new SkillTreePanel()
    panel.visible = true
    panel.unspentSkillPoints = 5

    const mockCtx = {
      save: vi.fn(),
      restore: vi.fn(),
      drawImage: vi.fn(),
      fillRect: vi.fn(),
      strokeRect: vi.fn(),
      fillStyle: '',
      strokeStyle: '',
      lineWidth: 1,
      globalAlpha: 1,
    } as unknown as CanvasRenderingContext2D

    const mockFont = {
      drawText: vi.fn(),
      measureText: vi.fn(() => 50),
    } as unknown as D2FontRenderer

    const mockSpImg = {
      complete: true,
      naturalWidth: 135,
      naturalHeight: 23,
    } as unknown as HTMLImageElement

    panel.draw(mockCtx, {
      borderRightImg: null,
      skillPointsImg: mockSpImg,
      buySellBtnImg: null,
    }, mockFont)

    // Verify skillpoints banner drawn at (ox + 60, oy + 395)
    expect(mockCtx.drawImage).toHaveBeenCalledWith(
      mockSpImg,
      SKILL_PANEL_ORIGIN.x + Math.round((256 - 135) / 2),
      SKILL_PANEL_ORIGIN.y + 395,
      135,
      23,
    )

    // Verify when unspentSkillPoints = 0, banner is NOT drawn
    vi.clearAllMocks()
    panel.unspentSkillPoints = 0
    panel.draw(mockCtx, {
      borderRightImg: null,
      skillPointsImg: mockSpImg,
      buySellBtnImg: null,
    }, mockFont)

    expect(mockCtx.drawImage).not.toHaveBeenCalledWith(
      mockSpImg,
      expect.anything(),
      expect.anything(),
      expect.anything(),
      expect.anything(),
    )
  })
})