from __future__ import annotations

import os

from .models import DryRunCandidate, DryRunReport, ProcessGroup


def build_dry_run(groups: list[ProcessGroup], *, current_pid: int | None = None) -> DryRunReport:
    current_pid = os.getpid() if current_pid is None else current_pid
    candidates: list[DryRunCandidate] = []
    exclusions: list[str] = []

    for group in groups:
        for node in group.stale_candidates:
            if node.sample.pid == current_pid:
                exclusions.append(f"PID {node.sample.pid}: dashboard self-process")
                continue
            if node.sample.uid not in {-1, os.getuid()}:
                exclusions.append(f"PID {node.sample.pid}: not current UID")
                continue
            if not (node.classification.is_bridge or node.classification.is_mcp):
                exclusions.append(f"PID {node.sample.pid}: not MCP/bridge")
                continue

            reasons = tuple(node.stale_reasons + node.risk_reasons + group.risk_reasons)
            candidates.append(
                DryRunCandidate(
                    pid=node.sample.pid,
                    process_key=node.sample.process_key,
                    known_class=node.classification.known_class,
                    age_seconds=node.sample.age_seconds,
                    rss_bytes=node.sample.rss_bytes,
                    command=node.sample.argv_display,
                    reasons=reasons or ("stale MCP/bridge candidate",),
                )
            )

    candidates.sort(key=lambda item: (-item.age_seconds, item.pid))
    return DryRunReport(candidates=tuple(candidates), exclusions=tuple(exclusions))