"""
Locust E2E Test Suite for Elemes LMS.

Auto-generated test scenarios from content/ folder via content_parser.py.
Reads test_data.json to know which lessons exist and their types.

Usage (from elemes/load-test/):
    1. python content_parser.py          # generate test_data.json
    2. locust -f locustfile.py           # open web UI at http://localhost:8089
       → Set host to your Elemes backend URL in the web UI

Environment variables:
    VELXIO_HOST  — Velxio backend URL for Arduino compilation
                   (default: http://localhost:8001)

All API paths hit the Flask backend directly (no /api prefix needed
when targeting Flask at :5000). Arduino compile hits Velxio backend.
"""

import json
import logging
import os
import random
import time

import requests
from locust import HttpUser, task, between, events

# ---------------------------------------------------------------------------
# Load test data
# ---------------------------------------------------------------------------

TEST_DATA_FILE = os.path.join(os.path.dirname(__file__), 'test_data.json')

def load_test_data() -> dict:
    """Load test_data.json generated by content_parser.py."""
    if not os.path.exists(TEST_DATA_FILE):
        raise FileNotFoundError(
            f"{TEST_DATA_FILE} not found. "
            f"Run 'python content_parser.py' first."
        )
    with open(TEST_DATA_FILE, 'r', encoding='utf-8') as f:
        return json.load(f)


try:
    TEST_DATA = load_test_data()
except FileNotFoundError as e:
    logging.error(str(e))
    TEST_DATA = {'token': '', 'teacher_token': '', 'lessons': []}

TOKENS = TEST_DATA.get('tokens', [])
TEACHER_TOKEN = TEST_DATA.get('teacher_token', '')
ALL_LESSONS = TEST_DATA.get('lessons', [])

# Velxio backend URL for Arduino compilation
VELXIO_HOST = os.environ.get('VELXIO_HOST', 'http://localhost:8001')

# Pre-filter lessons by type for task assignment
C_LESSONS = [l for l in ALL_LESSONS if l['type'] == 'c' and l.get('solution_code')]
PYTHON_LESSONS = [l for l in ALL_LESSONS if l['type'] == 'python' and l.get('solution_python')]
HYBRID_LESSONS = [l for l in ALL_LESSONS if l['type'] == 'hybrid']
ARDUINO_LESSONS = [l for l in ALL_LESSONS if l['type'] == 'arduino']
COMPILABLE_LESSONS = C_LESSONS + PYTHON_LESSONS + [
    l for l in HYBRID_LESSONS if l.get('solution_code') or l.get('solution_python')
]


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def check_key_text(code: str, key_text: str) -> bool:
    """Client-side key_text check (mirrors exercise.ts logic)."""
    if not key_text.strip():
        return True
    keys = [k.strip() for k in key_text.split('\n') if k.strip()]
    return all(k in code for k in keys)


# ---------------------------------------------------------------------------
# Locust User
# ---------------------------------------------------------------------------

class ElemesStudent(HttpUser):
    """
    Simulates a student interacting with the Elemes LMS.

    Each user logs in once (on_start), then performs weighted tasks
    that mirror real student behavior.
    """

    wait_time = between(1, 5)

    def on_start(self):
        """Login once when user spawns."""
        self.token = random.choice(TOKENS) if TOKENS else ''
        resp = self.client.post(
            '/login',
            json={'token': self.token},
            name='/login'
        )
        data = resp.json()
        if not data.get('success'):
            logging.warning(f"Login failed: {data.get('message')}")

    # ── Task 1: Browse Lessons (weight=3) ──────────────────────────────

    @task(3)
    def browse_lessons(self):
        """Fetch lesson list — simulates landing on home page."""
        with self.client.get('/lessons', name='/lessons', catch_response=True) as resp:
            data = resp.json()
            lessons = data.get('lessons', [])
            if len(lessons) == 0:
                resp.failure("No lessons returned")
            elif len(lessons) != len(ALL_LESSONS):
                resp.failure(
                    f"Expected {len(ALL_LESSONS)} lessons, got {len(lessons)}"
                )

    # ── Task 2: View Lesson Detail (weight=5) ──────────────────────────

    @task(5)
    def view_lesson_detail(self):
        """Fetch a random lesson's detail JSON."""
        if not ALL_LESSONS:
            return

        lesson = random.choice(ALL_LESSONS)
        slug = lesson['slug']

        with self.client.get(
            f'/lesson/{slug}.json',
            name='/lesson/[slug].json',
            catch_response=True
        ) as resp:
            data = resp.json()

            if 'error' in data:
                resp.failure(f"Lesson {slug} not found")
                return

            # Validate fields based on type
            if lesson['type'] == 'arduino':
                if not data.get('initial_code_arduino'):
                    resp.failure(f"{slug}: missing initial_code_arduino")
                if not data.get('velxio_circuit'):
                    resp.failure(f"{slug}: missing velxio_circuit")
                # Validate velxio_circuit is valid JSON
                try:
                    json.loads(data['velxio_circuit'])
                except (json.JSONDecodeError, TypeError):
                    resp.failure(f"{slug}: velxio_circuit is not valid JSON")
            elif lesson['type'] in ('c', 'hybrid'):
                if not data.get('initial_code'):
                    resp.failure(f"{slug}: missing initial_code")
            elif lesson['type'] == 'python':
                if not data.get('initial_python') and not data.get('initial_code'):
                    resp.failure(f"{slug}: missing initial code")

    # ── Task 3: Compile C Lesson (weight=4) ────────────────────────────

    @task(4)
    def compile_c_lesson(self):
        """Compile a C lesson's solution and validate output."""
        if not C_LESSONS:
            return

        lesson = random.choice(C_LESSONS)
        code = lesson.get('solution_code', lesson.get('initial_code_c', ''))
        expected = lesson.get('expected_output', '')

        if not code:
            return

        with self.client.post(
            '/compile',
            json={'code': code, 'language': 'c'},
            name='/compile [C]',
            catch_response=True
        ) as resp:
            data = resp.json()

            if not data.get('success'):
                resp.failure(f"Compile failed: {data.get('error', 'unknown')}")
                return

            output = data.get('output', '')

            # Validate expected output
            if expected and expected.strip() not in output:
                resp.failure(
                    f"{lesson['slug']}: expected '{expected.strip()[:50]}' "
                    f"not in output '{output[:50]}'"
                )
                return

            # Validate key_text
            key_text = lesson.get('key_text', '')
            if key_text and not check_key_text(code, key_text):
                resp.failure(f"{lesson['slug']}: key_text check failed")

    # ── Task 4: Compile Python Lesson (weight=3) ───────────────────────

    @task(3)
    def compile_python_lesson(self):
        """Compile a Python lesson's solution and validate output."""
        if not PYTHON_LESSONS:
            return

        lesson = random.choice(PYTHON_LESSONS)
        code = lesson.get('solution_python', lesson.get('initial_python', ''))
        expected = lesson.get('expected_output_python', lesson.get('expected_output', ''))

        if not code:
            return

        with self.client.post(
            '/compile',
            json={'code': code, 'language': 'python'},
            name='/compile [Python]',
            catch_response=True
        ) as resp:
            data = resp.json()

            if not data.get('success'):
                resp.failure(f"Compile failed: {data.get('error', 'unknown')}")
                return

            output = data.get('output', '')
            if expected and expected.strip() not in output:
                resp.failure(
                    f"{lesson['slug']}: expected '{expected.strip()[:50]}' "
                    f"not in output '{output[:50]}'"
                )

    # ── Task 5: Verify Arduino Lesson Structure (weight=2) ─────────────

    @task(2)
    def verify_arduino_lesson(self):
        """
        Verify an Arduino lesson's data structure.
        Validates JSON integrity of velxio_circuit and expected_wiring.
        """
        if not ARDUINO_LESSONS:
            return

        lesson = random.choice(ARDUINO_LESSONS)
        slug = lesson['slug']

        with self.client.get(
            f'/lesson/{slug}.json',
            name='/lesson/[arduino].json',
            catch_response=True
        ) as resp:
            data = resp.json()

            errors = []

            # Check required fields
            if not data.get('initial_code_arduino'):
                errors.append('missing initial_code_arduino')

            vc = data.get('velxio_circuit', '')
            if vc:
                try:
                    circuit = json.loads(vc)
                    if 'board' not in circuit:
                        errors.append('velxio_circuit missing board field')
                except (json.JSONDecodeError, TypeError):
                    errors.append('velxio_circuit invalid JSON')
            else:
                errors.append('missing velxio_circuit')

            # Check expected_wiring JSON validity if present
            ew = data.get('expected_wiring', '')
            if ew:
                try:
                    wiring = json.loads(ew)
                    if 'wires' not in wiring:
                        errors.append('expected_wiring missing wires array')
                except (json.JSONDecodeError, TypeError):
                    errors.append('expected_wiring invalid JSON')

            # Key text check against initial code
            key_text = lesson.get('key_text', '')
            initial_code = data.get('initial_code_arduino', '')
            if key_text and initial_code and not check_key_text(initial_code, key_text):
                errors.append('key_text not found in initial_code_arduino')

            if errors:
                resp.failure(f"{slug}: {'; '.join(errors)}")

    # ── Task 8: Compile Arduino via Velxio (weight=3) ──────────────────

    @task(3)
    def compile_arduino_lesson(self):
        """
        Compile an Arduino lesson's code via Velxio backend.
        Hits Velxio's POST /api/compile endpoint.
        Validates: compile success + hex_content returned.
        Note: serial output can only be validated in-browser (avr8js sim).
        """
        if not ARDUINO_LESSONS:
            return

        lesson = random.choice(ARDUINO_LESSONS)
        code = lesson.get('initial_code_arduino', '')
        if not code:
            return

        try:
            resp = requests.post(
                f'{VELXIO_HOST}/api/compile',
                json={'code': code, 'board_fqbn': 'arduino:avr:uno'},
                timeout=30
            )
            data = resp.json()

            if not data.get('success'):
                # Report as Locust failure for stats tracking
                self.environment.events.request.fire(
                    request_type='POST',
                    name='/api/compile [Arduino]',
                    response_time=resp.elapsed.total_seconds() * 1000,
                    response_length=len(resp.content),
                    exception=Exception(
                        f"{lesson['slug']}: compile failed — "
                        f"{data.get('error', data.get('stderr', 'unknown'))}"
                    ),
                )
                return

            hex_content = data.get('hex_content', '')
            if not hex_content:
                self.environment.events.request.fire(
                    request_type='POST',
                    name='/api/compile [Arduino]',
                    response_time=resp.elapsed.total_seconds() * 1000,
                    response_length=len(resp.content),
                    exception=Exception(f"{lesson['slug']}: no hex_content"),
                )
                return

            # Success
            self.environment.events.request.fire(
                request_type='POST',
                name='/api/compile [Arduino]',
                response_time=resp.elapsed.total_seconds() * 1000,
                response_length=len(resp.content),
                exception=None,
            )

        except requests.RequestException as e:
            self.environment.events.request.fire(
                request_type='POST',
                name='/api/compile [Arduino]',
                response_time=0,
                response_length=0,
                exception=e,
            )

    # ── Task 6: Complete Lesson Flow (weight=2) ────────────────────────

    @task(2)
    def complete_lesson_flow(self):
        """
        Full flow: fetch lesson → compile (if possible) → track progress.
        Simulates a student completing a lesson.
        """
        if not ALL_LESSONS:
            return

        lesson = random.choice(ALL_LESSONS)
        slug = lesson['slug']

        # 1. Fetch lesson detail
        resp = self.client.get(
            f'/lesson/{slug}.json',
            name='/lesson/[slug].json (flow)'
        )
        if resp.status_code != 200:
            return

        # 2. Compile if it's a C or Python lesson with solution
        if lesson['type'] in ('c', 'hybrid') and lesson.get('solution_code'):
            self.client.post(
                '/compile',
                json={'code': lesson['solution_code'], 'language': 'c'},
                name='/compile (flow)'
            )
            time.sleep(0.5)  # Simulate student reading output

        elif lesson['type'] == 'python' and lesson.get('solution_python'):
            self.client.post(
                '/compile',
                json={'code': lesson['solution_python'], 'language': 'python'},
                name='/compile (flow)'
            )
            time.sleep(0.5)

        elif lesson['type'] == 'arduino' and lesson.get('initial_code_arduino'):
            try:
                requests.post(
                    f'{VELXIO_HOST}/api/compile',
                    json={'code': lesson['initial_code_arduino'],
                          'board_fqbn': 'arduino:avr:uno'},
                    timeout=30
                )
            except requests.RequestException:
                pass  # Non-critical in flow
            time.sleep(0.5)

        # 3. Track progress
        with self.client.post(
            '/track-progress',
            json={
                'token': self.token,
                'lesson_name': slug,
                'status': 'completed'
            },
            name='/track-progress',
            catch_response=True
        ) as resp:
            data = resp.json()
            if not data.get('success'):
                resp.failure(f"Track progress failed: {data.get('message')}")

    # ── Task 7: Progress Report (weight=1) ─────────────────────────────

    @task(1)
    def view_progress_report(self):
        """Fetch progress report (teacher perspective)."""
        if not TEACHER_TOKEN:
            return

        # Login as teacher
        self.client.post(
            '/login',
            json={'token': TEACHER_TOKEN},
            name='/login [teacher]'
        )

        with self.client.get(
            '/progress-report.json',
            name='/progress-report.json',
            catch_response=True
        ) as resp:
            data = resp.json()
            students = data.get('students', [])
            lessons = data.get('lessons', [])

            if not lessons:
                resp.failure("No lessons in progress report")

        # Re-login as student for subsequent tasks
        self.client.post(
            '/login',
            json={'token': self.token},
            name='/login [re-auth]'
        )


# ---------------------------------------------------------------------------
# Event hooks
# ---------------------------------------------------------------------------

@events.test_start.add_listener
def on_test_start(environment, **kwargs):
    """Log test configuration at start."""
    stats = TEST_DATA.get('stats', {})
    logging.info("=" * 60)
    logging.info("  Elemes LMS — Locust E2E Test")
    logging.info("=" * 60)
    logging.info(f"  Lessons: {stats.get('total', 0)} total")
    logging.info(f"    C: {stats.get('c', 0)}, Python: {stats.get('python', 0)}, "
                 f"Hybrid: {stats.get('hybrid', 0)}, Arduino: {stats.get('arduino', 0)}")
    logging.info(f"    Compilable: {stats.get('compilable', 0)}")
    logging.info(f"  Tokens: {len(TOKENS)} loaded")
    logging.info(f"  Velxio: {VELXIO_HOST}")
    logging.info("=" * 60)