# =============================================================================
# Projet : AIR — Accounting Intermediate Representation
# Auteur : Simon-Pierre Boucher
# Contact : contact@spboucher.ai
# Fichier : diagnostics.py
# Description : Clang-style diagnostics — precise location, cause, suggestion.
# =============================================================================
"""Compiler-quality diagnostics for AIC.

Modeled on clang: every diagnostic names WHERE (event id / field path),
WHAT (computed cause, e.g. the exact imbalance), and HOW TO FIX (suggestion).
Errors abort compilation; warnings and notes ride along in the result.
"""
from __future__ import annotations

import enum
from dataclasses import dataclass


class Severity(enum.Enum):
    ERROR = "error"
    WARNING = "warning"
    NOTE = "note"


@dataclass(frozen=True, slots=True)
class Diagnostic:
    code: str                 # e.g. "AIR-E101"
    severity: Severity
    message: str
    location: str             # e.g. "event evt_01H..., field items[0].unit_price"
    suggestion: str | None = None
    origin_pass: str | None = None

    def render(self) -> str:
        head = f"{self.severity.value}[{self.code}]: {self.message}"
        lines = [head, f"  --> {self.location}"]
        if self.origin_pass:
            lines.append(f"  pass: {self.origin_pass}")
        if self.suggestion:
            lines.append(f"  help: {self.suggestion}")
        return "\n".join(lines)


class CompilationError(Exception):
    """Raised when any ERROR diagnostic is produced; carries all diagnostics."""

    def __init__(self, diagnostics: list[Diagnostic]):
        self.diagnostics = diagnostics
        errors = [d for d in diagnostics if d.severity is Severity.ERROR]
        super().__init__(
            f"{len(errors)} error(s):\n" + "\n".join(d.render() for d in errors)
        )