/**
 * KDL IR byte-parity — the mizan-ts `buildIr()` against the canonical Python
 * `build_ir()` (`cores/mizan-python/src/mizan_core/ir.py`).
 *
 * The IR is the codegen contract. A TypeScript backend can only feed
 * `protocol/mizan-codegen` if it emits the same KDL the Python/Rust backends
 * emit for the same registry. This test reconstructs the AFI fixture in both
 * languages, subprocesses the live Python emitter, and asserts byte-equality —
 * the same discipline `protocol/mizan-codegen/tests/python_parity.rs` applies.
 */

import { describe, test, expect, beforeEach } from 'bun:test'
import { execFileSync } from 'child_process'
import { existsSync } from 'fs'
import { resolve } from 'path'
import { buildIr, clearRegistry } from '../src'
import { registerFixture } from './ir-fixture'

const REPO_ROOT = resolve(import.meta.dir, '../../..')
const MIZAN_PYTHON = resolve(REPO_ROOT, 'cores/mizan-python')

/**
 * Reconstruct the AFI fixture in Python via `mizan_core` only (no backend
 * adapter dependency) and emit `build_ir()`. This is the cross-language oracle:
 * the same registrations the TS fixture makes, run through the reference
 * emitter.
 */
const PY_FIXTURE = String.raw`
import sys
from typing import Optional
from pydantic import BaseModel
from mizan_core.client.function import client
from mizan_core import registry as reg
from mizan_core.ir import build_ir

reg.clear_registry()

class EchoOutput(BaseModel):
    message: str

class WhoamiOutput(BaseModel):
    email: str
    authenticated: bool

class ProfileOutput(BaseModel):
    user_id: int
    name: str

class OrderOutput(BaseModel):
    id: int
    user_id: int
    total: int

class StatusOutput(BaseModel):
    ok: bool

@client
def echo(request, text: str) -> EchoOutput: ...

@client
def whoami(request) -> WhoamiOutput: ...

@client(context="user")
def user_profile(request, user_id: int) -> ProfileOutput: ...

@client(context="user")
def user_orders(request, user_id: int) -> list[OrderOutput]: ...

@client(affects="user")
def update_profile(request, user_id: int, name: str) -> StatusOutput: ...

@client
def find_user(request, user_id: int) -> Optional[ProfileOutput]: ...

@client(merge="user")
def rename_user(request, user_id: int, name: str) -> ProfileOutput: ...

for f in [echo, whoami, user_profile, user_orders, update_profile, find_user, rename_user]:
    reg.register(f, f.__name__)

sys.stdout.write(build_ir())
`

function pythonBuildIr(): string {
    return execFileSync(
        'uv',
        ['run', '--project', MIZAN_PYTHON, 'python', '-c', PY_FIXTURE],
        { encoding: 'utf-8' },
    )
}

const UV_AVAILABLE = (() => {
    try {
        execFileSync('uv', ['--version'], { stdio: 'ignore' })
        return existsSync(resolve(MIZAN_PYTHON, 'pyproject.toml'))
    } catch {
        return false
    }
})()

describe('KDL IR — buildIr()', () => {
    beforeEach(() => clearRegistry())

    test('emits the canonical type / function / context sections', () => {
        registerFixture()
        const kdl = buildIr()

        // Types are alphabetical; output structs renamed to <camel>Output.
        expect(kdl).toContain('type "OrderOutput" {')
        expect(kdl).toContain('type "echoInput" {')
        expect(kdl).toContain('type "findUserOutput" {')
        expect(kdl).toContain('type "userOrdersOutput" {')

        // Functions alphabetical, with transport + context/affects/merge leaves.
        expect(kdl).toContain('function "echo" {')
        expect(kdl).toContain('    camel "echo"')
        expect(kdl).toContain('    has-input #true')
        expect(kdl).toContain('    output-nullable #true') // find_user
        expect(kdl).toContain('    affects "user"') // update_profile
        expect(kdl).toContain('    merge "user"') // rename_user

        // Context section with shared param elevation.
        expect(kdl).toContain('context "user" {')
        expect(kdl).toContain('        shared-by "user_orders"')
        expect(kdl).toContain('        shared-by "user_profile"')
    })

    test('has-input #false for a no-arg function', () => {
        registerFixture()
        const kdl = buildIr()
        const whoami = kdl.slice(kdl.indexOf('function "whoami" {'))
        expect(whoami).toContain('has-input #false')
        expect(whoami).not.toContain('input "whoamiInput"')
    })

    test.skipIf(!UV_AVAILABLE)(
        'byte-identical to the Python build_ir() (cores/mizan-python)',
        () => {
            registerFixture()
            const tsKdl = buildIr()
            const pyKdl = pythonBuildIr()

            // Line-by-line first so a divergence names the offending line.
            const tsLines = tsKdl.split('\n')
            const pyLines = pyKdl.split('\n')
            const n = Math.max(tsLines.length, pyLines.length)
            for (let i = 0; i < n; i++) {
                if (tsLines[i] !== pyLines[i]) {
                    throw new Error(
                        `KDL diverges at line ${i + 1}:\n` +
                            `  python: ${JSON.stringify(pyLines[i])}\n` +
                            `  ts:     ${JSON.stringify(tsLines[i])}`,
                    )
                }
            }
            expect(tsKdl).toBe(pyKdl)
        },
    )
})