from .models import RequirementNode, NodeType
from .schemas import QualityReport


def validate_requirement(node: RequirementNode, children: list[RequirementNode]) -> QualityReport:
    """Run quality gates on a requirement node.

    Quality gates:
    1. Traceable — auto-calculated: has parent (non-pillar) + description
    2. Measurable — user toggle (manually set by the user)
    3. Consistent — user toggle (manually set by the user)
    4. Single-purpose — user toggle (manually set by the user)
    """
    errors: list[str] = []
    warnings: list[str] = []

    # 1. Traceable — auto-calculated
    traceable = True
    if node.node_type != NodeType.pillar:
        if not node.parent_id:
            errors.append("Non-pillar node must have a parent (traceability)")
            traceable = False
        if not node.description:
            warnings.append("Missing description — hard to trace how this serves parent")
    else:
        if not node.description:
            warnings.append("Pillar should have a description explaining its purpose")

    # 2. Measurable — user toggle, but forced false without test_spec
    measurable = bool(node.measurable)
    if not node.acceptance_criteria:
        warnings.append("Missing acceptance criteria")
    if not node.test_spec:
        errors.append("Missing test specification (GIVEN/WHEN/THEN) — cannot be measurable")
        measurable = False

    # 3. Consistent — user toggle
    consistent = bool(node.consistent)

    # 4. Single-purpose — user toggle, but warn on heuristic
    single_purpose = bool(node.single_purpose)
    title_lower = node.title.lower()
    if " and " in title_lower and " and " not in title_lower.split("(")[0]:
        warnings.append("Title contains 'and' — may serve multiple purposes")

    return QualityReport(
        traceable=traceable,
        measurable=measurable,
        consistent=consistent,
        single_purpose=single_purpose,
        errors=errors,
        warnings=warnings,
        valid=len(errors) == 0,
    )