"""R7 — pluggable SelectorPolicy seam + local-OSS (Ollama) agent arm.

Covers the RQ3 agent-backend build detail:
  * the policy seam resolves static/random/agent(heuristic) identically to the
    prior inline strategies (no behavioural regression);
  * the Ollama agent backend picks a valid rebuild circuit, is decision-cached
    (replay-deterministic), falls back to the local heuristic on any model/parse
    failure (never breaks a run), and records model+digest provenance;
  * the Claude Code arm is EXPLORATORY-only — it refuses to run and makes no paid
    call.

The live Ollama cell is skipped where no local server/model is present, so the
suite stays green offline. This is a *measurement* decision path (a local call to
localhost), not relay traffic — containment is untouched.
"""

import json
import urllib.request

import pytest

from cmd_chat.sor.agent_selector import (
    DEFAULT_MODEL,
    ClaudeExploratoryPolicy,
    OllamaAgentPolicy,
)
from cmd_chat.sor.churn import churn_schedule
from cmd_chat.sor.selector import (
    HeuristicAgentPolicy,
    RandomPolicy,
    SelectorContext,
    StaticPolicy,
    make_policy,
    run_selection,
)

NODES = [f"n{i}" for i in range(8)]


def _ollama_ready() -> bool:
    try:
        with urllib.request.urlopen("http://localhost:11434/api/tags", timeout=5) as r:
            tags = json.loads(r.read().decode())
    except Exception:
        return False
    names = {m.get("name") for m in tags.get("models", [])}
    return DEFAULT_MODEL in names


live_ollama = pytest.mark.skipif(
    not _ollama_ready(),
    reason=f"requires a local Ollama server with {DEFAULT_MODEL}",
)


# --------------------------------------------------------------------------- #
# Policy seam.
# --------------------------------------------------------------------------- #
def test_make_policy_resolves_builtins():
    assert isinstance(make_policy("static"), StaticPolicy)
    assert isinstance(make_policy("random"), RandomPolicy)
    assert isinstance(make_policy("agent", "heuristic"), HeuristicAgentPolicy)
    assert isinstance(make_policy("agent", "ollama"), OllamaAgentPolicy)


def test_make_policy_rejects_unknown():
    with pytest.raises(ValueError):
        make_policy("nope")
    with pytest.raises(ValueError):
        make_policy("agent", "frontier-gpt")


def test_heuristic_prefers_least_churned():
    ctx = SelectorContext(seed=1, hops=3, kill_counts={"n0": 5, "n1": 5, "n2": 0})
    chosen = HeuristicAgentPolicy().choose(NODES, ctx)
    # Nodes with 0 kills (n2..n7) outrank the twice-killed n0/n1.
    assert "n0" not in chosen and "n1" not in chosen
    assert len(chosen) == 3 and len(set(chosen)) == 3


# --------------------------------------------------------------------------- #
# Ollama agent backend — fallback path is testable without any server.
# --------------------------------------------------------------------------- #
def test_agent_falls_back_deterministically_when_model_unreachable():
    # Point at a dead port -> every model query fails -> deterministic heuristic.
    pol = OllamaAgentPolicy(host="http://127.0.0.1:1", timeout=0.5)
    ctx = SelectorContext(seed=7, hops=3, kill_counts={"n0": 9})
    chosen = pol.choose(NODES, ctx)
    assert chosen == HeuristicAgentPolicy().choose(NODES, ctx)
    assert pol.decisions()[-1]["source"] == "fallback"
    # And it is cached: a second identical call is served from cache.
    again = pol.choose(NODES, ctx)
    assert again == chosen
    assert pol.decisions()[-1]["source"] == "cache"


def test_agent_validity_guard_rejects_out_of_pool():
    pol = OllamaAgentPolicy()
    assert pol._valid(["n0", "n1", "n2"], NODES, 3) is True
    assert pol._valid(["n0", "n0", "n2"], NODES, 3) is False   # dup
    assert pol._valid(["n0", "n1"], NODES, 3) is False          # wrong length
    assert pol._valid(["n0", "n1", "zzz"], NODES, 3) is False   # not in pool
    assert pol._valid("nope", NODES, 3) is False


def test_agent_provenance_shape():
    pol = OllamaAgentPolicy(host="http://127.0.0.1:1", timeout=0.5)
    ctx = SelectorContext(seed=1, hops=3)
    pol.choose(NODES, ctx)
    prov = pol.provenance()
    assert prov["policy"] == "agent-ollama"
    assert prov["model"] == DEFAULT_MODEL
    assert prov["options"]["temperature"] == 0
    assert prov["decisions"]["total"] == 1


# --------------------------------------------------------------------------- #
# Claude arm — EXPLORATORY only, never spends.
# --------------------------------------------------------------------------- #
def test_claude_arm_is_exploratory_and_refuses():
    pol = ClaudeExploratoryPolicy()
    with pytest.raises(NotImplementedError):
        pol.choose(NODES, SelectorContext(seed=1, hops=3))
    prov = pol.provenance()
    assert prov["paid_calls"] is False and prov["wired"] is False


def test_run_selection_agent_backend_via_string():
    # agent+heuristic through run_selection rebuilds every dropped circuit and
    # records policy provenance.
    seed = 0xBADC0DE
    sched = churn_schedule(seed, NODES, steps=60, kill_prob_pct=35)
    res = run_selection(seed, NODES, hops=3, schedule=sched,
                        strategy="agent", agent_backend="heuristic")
    assert res.strategy == "agent"
    assert res.every_drop_rebuilt
    assert res.policy_provenance["policy"] == "agent-heuristic"


def test_run_selection_writes_selector_sidecar(tmp_path):
    seed = 42
    sched = churn_schedule(seed, NODES, steps=20)
    res = run_selection(seed, NODES, hops=3, schedule=sched,
                        strategy="agent", agent_backend="ollama",
                        host="http://127.0.0.1:1", timeout=0.5,
                        run_dir=tmp_path)
    sidecar = json.loads((tmp_path / "selector.json").read_text())
    assert sidecar["provenance"]["policy"] == "agent-ollama"
    assert "decisions" in sidecar  # per-state audit log present
    assert res.policy_provenance["model"] == DEFAULT_MODEL


# --------------------------------------------------------------------------- #
# Live cell — real local model (skipped if Ollama absent).
# --------------------------------------------------------------------------- #
@live_ollama
def test_live_ollama_picks_valid_circuit_and_pins_digest():
    pol = OllamaAgentPolicy()
    ctx = SelectorContext(seed=123, hops=3, kill_counts={"n0": 3, "n1": 1})
    chosen = pol.choose(NODES, ctx)
    assert chosen is not None and len(chosen) == 3 and len(set(chosen)) == 3
    assert all(c in set(NODES) for c in chosen)
    # Cached replay is byte-identical regardless of model nondeterminism.
    assert pol.choose(NODES, ctx) == chosen
    # The exact model weights are pinned for provenance.
    assert pol.provenance()["model_digest"]


@live_ollama
def test_live_ollama_run_selection_rebuilds_every_drop(tmp_path):
    seed = 2024
    sched = churn_schedule(seed, NODES, steps=40, kill_prob_pct=35)
    res = run_selection(seed, NODES, hops=3, schedule=sched,
                        strategy="agent", agent_backend="ollama",
                        run_dir=tmp_path)
    assert res.every_drop_rebuilt
    assert (tmp_path / "selector.json").exists()