import { describe, expect, it } from 'vitest'
import { clampLimit, sliceUtf8, truncateJsonBudget, truncateRows } from '../../src/format.js'

describe('clampLimit', () => {
    it('returns fallback when undefined', () => {
        expect(clampLimit(undefined)).toBe(100)
        expect(clampLimit(undefined, 7)).toBe(7)
    })
    it('clamps to [1, max]', () => {
        expect(clampLimit(0)).toBe(1)
        expect(clampLimit(99999)).toBe(1000)
        expect(clampLimit(5000, 100, 2000)).toBe(2000)
    })
})

describe('truncateRows', () => {
    it('does not truncate when under limit', () => {
        expect(truncateRows([1, 2], 5)).toEqual({ rows: [1, 2], truncated: false })
    })
    it('truncates and flags when over limit', () => {
        expect(truncateRows([1, 2, 3], 2)).toEqual({ rows: [1, 2], truncated: true })
    })
})

describe('truncateJsonBudget', () => {
    it('passes small payloads through untouched', () => {
        const v = { a: 1 }
        expect(truncateJsonBudget(v, 1000)).toEqual({ body: v, truncated: false })
    })
    it('marks oversized payloads truncated', () => {
        const big = { s: 'x'.repeat(500) }
        const out = truncateJsonBudget(big, 100)
        expect(out.truncated).toBe(true)
        expect((out.body as { _truncated: boolean })._truncated).toBe(true)
    })
})

describe('sliceUtf8', () => {
    it('returns the string unchanged when it fits', () => {
        expect(sliceUtf8('hello', 100)).toBe('hello')
    })
    it('caps to a real UTF-8 byte budget', () => {
        const out = sliceUtf8('abcdef', 3)
        expect(Buffer.byteLength(out, 'utf8')).toBeLessThanOrEqual(3)
        expect(out).toBe('abc')
    })
    it('does not split a multi-byte code point at the boundary', () => {
        const out = sliceUtf8('aéé', 3)
        expect(Buffer.byteLength(out, 'utf8')).toBeLessThanOrEqual(3)
        expect(out).toBe('aé')
    })
})