"""Test workflow service — state-machine transitions for the Red/Blue validation flow.

Controls which state transitions are valid and exposes high-level helpers
for each step in the test lifecycle:

    draft → red_executing → blue_evaluating → in_review → validated / rejected
                                                                  ↓
                                                           rejected → draft

Every public function validates the transition, mutates the test, writes an
audit-log entry, and commits the session.
"""

import logging
from datetime import datetime

from sqlalchemy.orm import Session

from app.config import settings
from app.domain.exceptions import InvalidOperationError, InvalidTransitionError
from app.models.enums import TestState
from app.models.test import Test
from app.models.user import User
from app.services.audit_service import log_action
from app.services.notification_service import notify_test_state_change, create_notification

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Valid transition map
# ---------------------------------------------------------------------------

VALID_TRANSITIONS: dict[TestState, list[TestState]] = {
    TestState.draft:           [TestState.red_executing],
    TestState.red_executing:   [TestState.blue_evaluating],
    TestState.blue_evaluating: [TestState.in_review],
    TestState.in_review:       [TestState.validated, TestState.rejected],
    TestState.rejected:        [TestState.draft],
    TestState.validated:       [],  # terminal state
}


# ---------------------------------------------------------------------------
# Core helpers
# ---------------------------------------------------------------------------


def can_transition(test: Test, target_state: TestState) -> bool:
    """Return *True* if moving *test* to *target_state* is allowed."""
    current = test.state if isinstance(test.state, TestState) else TestState(test.state)
    return target_state in VALID_TRANSITIONS.get(current, [])


def transition_state(
    db: Session,
    test: Test,
    target_state: TestState,
    user: User,
    *,
    action_name: str = "transition_state",
    extra_details: dict | None = None,
) -> Test:
    """Validate and perform a state transition, log it, and commit.

    Raises :class:`InvalidTransitionError` when the transition is invalid.
    """
    if not can_transition(test, target_state):
        current = test.state if isinstance(test.state, TestState) else TestState(test.state)
        valid = [s.value for s in VALID_TRANSITIONS.get(current, [])]
        raise InvalidTransitionError(
            current_state=current.value,
            target_state=target_state.value,
            valid_transitions=valid,
        )

    previous_state = test.state.value if isinstance(test.state, TestState) else test.state
    test.state = target_state
    db.flush()

    details: dict = {
        "previous_state": previous_state,
        "new_state": target_state.value,
        "test_name": test.name,
        "technique_id": str(test.technique_id),
    }
    if extra_details:
        details.update(extra_details)

    log_action(
        db,
        user_id=user.id,
        action=action_name,
        entity_type="test",
        entity_id=test.id,
        details=details,
    )

    # Dispatch in-app notifications for the new state
    try:
        notify_test_state_change(db, test, target_state.value)
    except Exception as e:
        logger.warning("Notification failed for test %s: %s", test.id, e, exc_info=True)

    return test


# ---------------------------------------------------------------------------
# Lifecycle convenience functions
# ---------------------------------------------------------------------------


def start_execution(db: Session, test: Test, user: User) -> Test:
    """Move from ``draft`` → ``red_executing``.

    Typically called by a **red_tech** when they begin the attack.
    """
    test = transition_state(
        db, test, TestState.red_executing, user,
        action_name="start_execution",
    )
    test.execution_date = datetime.utcnow()
    db.commit()
    return test


def submit_red_evidence(db: Session, test: Test, user: User) -> Test:
    """Move from ``red_executing`` → ``blue_evaluating``.

    Called by **red_tech** once they have finished documenting the attack.
    """
    test = transition_state(
        db, test, TestState.blue_evaluating, user,
        action_name="submit_red_evidence",
    )
    db.commit()
    return test


def submit_blue_evidence(db: Session, test: Test, user: User) -> Test:
    """Move from ``blue_evaluating`` → ``in_review``.

    Called by **blue_tech** once they have finished documenting detection.
    """
    test = transition_state(
        db, test, TestState.in_review, user,
        action_name="submit_blue_evidence",
    )
    db.commit()
    return test


def validate_as_red_lead(
    db: Session,
    test: Test,
    user: User,
    validation_status: str,
    notes: str | None = None,
) -> Test:
    """Record Red Lead's validation decision.

    *validation_status* must be ``"approved"`` or ``"rejected"``.
    After recording the decision, :func:`check_dual_validation` is called
    to potentially advance the test to ``validated`` or ``rejected``.
    """
    current = test.state.value if isinstance(test.state, TestState) else test.state
    if test.state not in (TestState.in_review,):
        raise InvalidOperationError(
            f"Cannot validate red side while test is in '{current}' state (must be in_review)"
        )

    if validation_status not in ("approved", "rejected"):
        raise InvalidOperationError(
            "validation_status must be 'approved' or 'rejected'"
        )

    now = datetime.utcnow()
    test.red_validation_status = validation_status
    test.red_validated_by = user.id
    test.red_validated_at = now
    test.red_validation_notes = notes

    log_action(
        db,
        user_id=user.id,
        action="validate_as_red_lead",
        entity_type="test",
        entity_id=test.id,
        details={
            "validation_status": validation_status,
            "notes": notes,
            "technique_id": str(test.technique_id),
        },
    )

    check_dual_validation(db, test)
    return test


def validate_as_blue_lead(
    db: Session,
    test: Test,
    user: User,
    validation_status: str,
    notes: str | None = None,
) -> Test:
    """Record Blue Lead's validation decision.

    *validation_status* must be ``"approved"`` or ``"rejected"``.
    After recording the decision, :func:`check_dual_validation` is called
    to potentially advance the test to ``validated`` or ``rejected``.
    """
    current = test.state.value if isinstance(test.state, TestState) else test.state
    if test.state not in (TestState.in_review,):
        raise InvalidOperationError(
            f"Cannot validate blue side while test is in '{current}' state (must be in_review)"
        )

    if validation_status not in ("approved", "rejected"):
        raise InvalidOperationError(
            "validation_status must be 'approved' or 'rejected'"
        )

    now = datetime.utcnow()
    test.blue_validation_status = validation_status
    test.blue_validated_by = user.id
    test.blue_validated_at = now
    test.blue_validation_notes = notes

    log_action(
        db,
        user_id=user.id,
        action="validate_as_blue_lead",
        entity_type="test",
        entity_id=test.id,
        details={
            "validation_status": validation_status,
            "notes": notes,
            "technique_id": str(test.technique_id),
        },
    )

    check_dual_validation(db, test)
    return test


def check_dual_validation(db: Session, test: Test) -> Test:
    """Evaluate both leads' decisions and advance the test if both have voted.

    - Both **approved** → ``validated``
    - Either **rejected** → ``rejected``
    - Otherwise no state change (waiting for the other lead).

    Commits only when the state actually changes.
    """
    red_status = test.red_validation_status
    blue_status = test.blue_validation_status

    if red_status == "rejected" or blue_status == "rejected":
        test.state = TestState.rejected
        db.commit()
        try:
            notify_test_state_change(db, test, "rejected")
        except Exception as e:
            logger.warning("Notification failed for test %s (rejected): %s", test.id, e, exc_info=True)
    elif red_status == "approved" and blue_status == "approved":
        test.state = TestState.validated
        db.commit()
        # Invalidate cached scores — a validation changes org-level numbers
        try:
            from app.services.score_cache import invalidate
            invalidate()
        except Exception as e:
            logger.warning("Score cache invalidation failed: %s", e, exc_info=True)
        try:
            notify_test_state_change(db, test, "validated")
        except Exception as e:
            logger.warning("Notification failed for test %s (validated): %s", test.id, e, exc_info=True)
    else:
        # One side hasn't voted yet — stay in_review, just flush
        db.commit()

    return test


def handle_remediation_completed(db: Session, test: Test, user: User) -> Test | None:
    """Create a re-test when remediation is completed.

    When a test's remediation_status changes to 'completed', this function
    creates a new test (retest) with the same base data to verify that the
    fix was effective.

    Prevents infinite loops by enforcing ``MAX_RETEST_COUNT``.

    Returns the new retest or *None* if the limit was reached.
    """
    # Always reference the original test, not an intermediate retest
    original_test_id = test.retest_of or test.id

    if test.retest_count >= settings.MAX_RETEST_COUNT:
        # Max retests reached — notify and bail out
        if test.created_by:
            create_notification(
                db,
                user_id=test.created_by,
                type="max_retests_reached",
                title="Maximum retests reached",
                message=(
                    f'Test "{test.name}" has reached the maximum of '
                    f'{settings.MAX_RETEST_COUNT} retests. Manual review required.'
                ),
                entity_type="test",
                entity_id=test.id,
            )

        log_action(
            db,
            user_id=user.id,
            action="max_retests_reached",
            entity_type="test",
            entity_id=test.id,
            details={
                "retest_count": test.retest_count,
                "max_allowed": settings.MAX_RETEST_COUNT,
                "original_test_id": str(original_test_id),
            },
        )
        return None

    retest = Test(
        technique_id=test.technique_id,
        name=f"[Retest #{test.retest_count + 1}] {test.name.replace(f'[Retest #{test.retest_count}] ', '')}",
        description=test.description,
        platform=test.platform,
        procedure_text=test.procedure_text,
        tool_used=test.tool_used,
        state=TestState.draft,
        created_by=test.created_by,
        retest_of=original_test_id,
        retest_count=test.retest_count + 1,
    )
    db.add(retest)
    db.flush()

    log_action(
        db,
        user_id=user.id,
        action="create_retest",
        entity_type="test",
        entity_id=retest.id,
        details={
            "original_test_id": str(original_test_id),
            "retest_number": retest.retest_count,
            "source_test_id": str(test.id),
        },
    )

    # Notify the test creator and any red_tech users
    if test.created_by:
        create_notification(
            db,
            user_id=test.created_by,
            type="retest_created",
            title="Re-test created",
            message=(
                f'A re-test has been automatically created for "{test.name}" '
                f'after remediation was completed.'
            ),
            entity_type="test",
            entity_id=retest.id,
        )

    db.commit()
    db.refresh(retest)
    return retest


def get_retest_chain(db: Session, test_id) -> list[Test]:
    """Return the full chain of retests for a given test.

    Includes the original test and all subsequent retests, ordered
    by retest_count.
    """
    import uuid as _uuid

    tid = _uuid.UUID(str(test_id)) if not isinstance(test_id, _uuid.UUID) else test_id

    # Find the original test first
    test = db.query(Test).filter(Test.id == tid).first()
    if not test:
        return []

    original_id = test.retest_of or test.id

    # Get original
    original = db.query(Test).filter(Test.id == original_id).first()
    if not original:
        return [test]

    # Get all retests of the original
    retests = (
        db.query(Test)
        .filter(Test.retest_of == original_id)
        .order_by(Test.retest_count)
        .all()
    )

    return [original] + retests


def reopen_test(db: Session, test: Test, user: User) -> Test:
    """Move a ``rejected`` test back to ``draft``, clearing validation fields.

    This allows the teams to redo the test cycle.
    """
    test = transition_state(
        db, test, TestState.draft, user,
        action_name="reopen_test",
    )

    # Clear dual-validation fields
    test.red_validation_status = None
    test.red_validated_by = None
    test.red_validated_at = None
    test.red_validation_notes = None

    test.blue_validation_status = None
    test.blue_validated_by = None
    test.blue_validated_at = None
    test.blue_validation_notes = None

    db.commit()
    return test