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

import { truncateText } from "@/utils/textUtils"

describe("truncateText", () => {
  const createMockContext = (charWidth: number = 10) => {
    return {
      measureText: vi.fn((text: string) => ({ width: text.length * charWidth })),
    } as unknown as CanvasRenderingContext2D
  }

  it("should return original text if it fits within maxWidth", () => {
    const ctx = createMockContext()
    const result = truncateText(ctx, "Short", 100)
    expect(result).toBe("Short")
  })

  it("should return original text if maxWidth is 0 or negative", () => {
    const ctx = createMockContext()
    expect(truncateText(ctx, "Text", 0)).toBe("Text")
    expect(truncateText(ctx, "Text", -10)).toBe("Text")
  })

  it("should truncate text and add ellipsis when text is too long", () => {
    const ctx = createMockContext(10) // 10 pixels per character
    const result = truncateText(ctx, "This is a very long text", 100)
    // 100px total, "..." takes 30px, leaving 70px for text (7 chars)
    expect(result).toBe("This is...")
  })

  it("should use custom ellipsis when provided", () => {
    const ctx = createMockContext(10)
    const result = truncateText(ctx, "This is a very long text", 100, "…")
    // 100px total, "…" takes 10px, leaving 90px for text (9 chars)
    expect(result).toBe("This is a…")
  })

  it("should return only ellipsis if available width is too small", () => {
    const ctx = createMockContext(10)
    const result = truncateText(ctx, "Text", 20) // Only room for 2 chars, but "..." needs 3
    expect(result).toBe("...")
  })

  it("should handle empty text", () => {
    const ctx = createMockContext()
    const result = truncateText(ctx, "", 100)
    expect(result).toBe("")
  })

  it("should use binary search efficiently", () => {
    const ctx = createMockContext(10)
    const longText = "A".repeat(100) // 100 characters

    const result = truncateText(ctx, longText, 200) // Room for 20 chars total
    expect(result).toBe(`${"A".repeat(17)}...`) // 17 chars + "..." = 20 chars = 200px

    // Verify binary search efficiency - should not measure every possible substring
    // Binary search for 100 chars should take around log2(100) ≈ 7 iterations
    // Plus a few extra calls for measuring the full text and ellipsis
    const callCount = (ctx.measureText as any).mock.calls.length
    expect(callCount).toBeLessThan(20)
    expect(callCount).toBeGreaterThan(5)
  })

  it("should handle unicode characters correctly", () => {
    const ctx = createMockContext(10)
    const result = truncateText(ctx, "Hello 👋 World", 80)
    // Assuming each char (including emoji) is 10px, total is 130px
    // 80px total, "..." takes 30px, leaving 50px for text (5 chars)
    expect(result).toBe("Hello...")
  })

  it("should handle exact boundary cases", () => {
    const ctx = createMockContext(10)

    // Text exactly fits
    expect(truncateText(ctx, "Exact", 50)).toBe("Exact") // 5 chars = 50px

    // Text is exactly 1 pixel too long
    expect(truncateText(ctx, "Exact!", 50)).toBe("Ex...") // 6 chars = 60px, truncated
  })
})