import { test, expect } from "bun:test"
import { toBytecode } from "#bytecode"
import { OpCode } from "#opcode"
import { VM } from "#vm"

test("string compilation", () => {
  const str = `
  PUSH 1
  PUSH 5
  ADD
`
  expect(toBytecode(str)).toEqual({
    instructions: [
      { op: OpCode.PUSH, operand: 0 },
      { op: OpCode.PUSH, operand: 1 },
      { op: OpCode.ADD },
    ],
    constants: [
      { type: 'number', value: 1 },
      { type: 'number', value: 5 }
    ]
  })
})


test("MAKE_FUNCTION - basic function", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION () .body
    PUSH 0
    PUSH 0
    CALL
    HALT
    .body:
    PUSH 42
    RETURN
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 42 })
})

test("MAKE_FUNCTION - function with parameters", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (x y) .add
    PUSH 10
    PUSH 20
    PUSH 2
    PUSH 0
    CALL
    HALT
    .add:
    LOAD x
    LOAD y
    ADD
    RETURN
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 30 })
})

test("MAKE_FUNCTION - function with default parameters", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (x y=100) .add
    PUSH 10
    PUSH 1
    PUSH 0
    CALL
    HALT
    .add:
    LOAD x
    LOAD y
    ADD
    RETURN
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 110 })
})

test("MAKE_FUNCTION - tail recursive countdown", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (n) .countdown
    STORE countdown
    LOAD countdown
    PUSH 5
    PUSH 1
    PUSH 0
    CALL
    HALT
    .countdown:
    LOAD n
    PUSH 0
    EQ
    JUMP_IF_FALSE .recurse
    PUSH "done"
    RETURN
    .recurse:
    LOAD countdown
    LOAD n
    PUSH 1
    SUB
    PUSH 1
    PUSH 0
    TAIL_CALL
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'string', value: 'done' })
})

test("MAKE_FUNCTION - multiple default values", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (a=1 b=2 c=3) .sum
    PUSH 0
    PUSH 0
    CALL
    HALT
    .sum:
    LOAD a
    LOAD b
    LOAD c
    ADD
    ADD
    RETURN
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 6 })
})

test("MAKE_FUNCTION - default with string", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (name="World") .greet
    PUSH 0
    PUSH 0
    CALL
    HALT
    .greet:
    LOAD name
    RETURN
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'string', value: 'World' })
})

test("semicolon comments are ignored", () => {
  const bytecode = toBytecode(`
    ; This is a comment
    PUSH 1    ; push one
    PUSH 5    ; push five
    ADD       ; add them
  `)

  expect(bytecode).toEqual({
    instructions: [
      { op: OpCode.PUSH, operand: 0 },
      { op: OpCode.PUSH, operand: 1 },
      { op: OpCode.ADD },
    ],
    constants: [
      { type: 'number', value: 1 },
      { type: 'number', value: 5 }
    ]
  })
})

test("semicolon comments work with functions", async () => {
  const bytecode = toBytecode(`
    MAKE_FUNCTION (x y) .add  ; function with two params
    PUSH 10                   ; first arg
    PUSH 20                   ; second arg
    PUSH 2                    ; positional count
    PUSH 0                    ; named count
    CALL                      ; call the function
    HALT
    .add:                     ; Function body starts here
    LOAD x                    ; load first param
    LOAD y                    ; load second param
    ADD                       ; add them
    RETURN                    ; return result
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 30 })
})

test("labels - basic jump", async () => {
  const bytecode = toBytecode(`
    JUMP .end
    PUSH 999
    .end:
    PUSH 42
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 42 })
})

test("labels - conditional jump", async () => {
  const bytecode = toBytecode(`
    PUSH 1
    JUMP_IF_FALSE .else
    PUSH 10
    JUMP .end
    .else:
    PUSH 20
    .end:
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 10 })
})

test("labels - loop", async () => {
  const bytecode = toBytecode(`
    PUSH 0
    STORE i
    .loop:
    LOAD i
    PUSH 3
    LT
    JUMP_IF_FALSE .end
    LOAD i
    PUSH 1
    ADD
    STORE i
    JUMP .loop
    .end:
    LOAD i
  `)

  const vm = new VM(bytecode)
  const result = await vm.run()
  expect(result).toEqual({ type: 'number', value: 3 })
})