"""Shared helpers used by both backends' resolve_plan steps.

Each helper owns one well-defined step of the per-bottle plan
resolution so docker and smolmachines don't repeat the same logic.
Backend-specific steps (container names, env-file, per-bottle
Dockerfile overrides, subnet allocation) stay in the backend's own
resolve_plan.py.
"""

from __future__ import annotations

import os
from dataclasses import replace
from datetime import datetime, timezone
from pathlib import Path

from ..agent_provider import AgentProvisionPlan
from ..bottle_state import (
    BottleMetadata,
    agent_state_dir,
    bottle_identity,
    egress_state_dir,
    git_gate_state_dir,
    supervise_state_dir,
    write_metadata,
)
from ..egress import Egress, EgressPlan
from ..git_gate import GitGate, GitGatePlan
from ..manifest import ManifestBottle
from ..supervise import Supervise, SupervisePlan
from . import BottleSpec


def mint_slug(spec: BottleSpec) -> str:
    """Return the bottle identity: the recorded identity for a resume,
    or a freshly minted one for a new start."""
    return spec.identity or bottle_identity(spec.agent_name)


def write_launch_metadata(
    slug: str, spec: BottleSpec, *, compose_project: str, backend: str,
) -> None:
    """Persist launch metadata so `cli.py resume <identity>` can
    reconstruct the spec. Idempotent — re-writes on resume with a
    refreshed started_at."""
    write_metadata(BottleMetadata(
        identity=slug,
        agent_name=spec.agent_name,
        cwd=spec.user_cwd if spec.copy_cwd else "",
        copy_cwd=spec.copy_cwd,
        started_at=datetime.now(timezone.utc).isoformat(),
        compose_project=compose_project,
        backend=backend,
        label=spec.label,
        color=spec.color,
    ))


def prepare_agent_state_dir(slug: str, spec: BottleSpec) -> tuple[Path, Path]:
    """Create the agent state subdir, write the prompt file.
    Returns (agent_dir, prompt_file)."""
    manifest = spec.manifest
    agent = manifest.agents[spec.agent_name]
    agent_dir = agent_state_dir(slug)
    agent_dir.mkdir(parents=True, exist_ok=True)
    prompt_file = agent_dir / "prompt.txt"
    prompt_file.write_text(agent.prompt or "")
    prompt_file.chmod(0o600)
    return agent_dir, prompt_file


def prepare_git_gate(bottle: ManifestBottle, slug: str) -> GitGatePlan:
    git_gate_dir = git_gate_state_dir(slug)
    git_gate_dir.mkdir(parents=True, exist_ok=True)
    return GitGate().prepare(bottle, slug, git_gate_dir)


def prepare_egress(
    bottle: ManifestBottle, slug: str, provision: AgentProvisionPlan,
) -> EgressPlan:
    egress_dir = egress_state_dir(slug)
    egress_dir.mkdir(parents=True, exist_ok=True)
    return Egress().prepare(bottle, slug, egress_dir, provision.egress_routes)


def prepare_supervise(
    bottle: ManifestBottle, slug: str, *, dockerfile_content: str = "",
) -> SupervisePlan | None:
    """Prepare the supervise sidecar state dir. Returns None when
    bottle.supervise is falsy."""
    if not bottle.supervise:
        return None
    supervise_dir = supervise_state_dir(slug)
    supervise_dir.mkdir(parents=True, exist_ok=True)
    return Supervise().prepare(slug, supervise_dir, dockerfile_content=dockerfile_content)


def merge_provision_env_vars(provision: AgentProvisionPlan) -> AgentProvisionPlan:
    """Fold provision.env_vars into guest_env (setdefault semantics)
    and return a new plan with the merged guest_env."""
    merged = dict(provision.guest_env)
    for key, val in provision.env_vars.items():
        merged.setdefault(key, val)
    return replace(provision, guest_env=merged)


def resolve_manifest_dockerfile(path_value: str, spec: BottleSpec) -> str:
    """Resolve a manifest-supplied dockerfile path relative to user_cwd."""
    path = Path(os.path.expanduser(path_value))
    if not path.is_absolute():
        path = Path(spec.user_cwd) / path
    return str(path)


__all__ = [
    "merge_provision_env_vars",
    "mint_slug",
    "prepare_agent_state_dir",
    "prepare_egress",
    "prepare_git_gate",
    "prepare_supervise",
    "resolve_manifest_dockerfile",
    "write_launch_metadata",
]