"""Deterministic per-(subject, operation) fixtures, built once and copied per trial.

Layout under ``<root>/pristine``: ``client/`` (repo under test), ``other/``

(second clone used to advance the remote), ``srv/`` (oak serve data dir or

Git bare ``remote.git``). ``meta.json`` records the pre-state every trial is

judged against (read with the independent readers, never the subject).

"""

from __future__ import annotations

import json

import shutil

from dataclasses import dataclass, field

from pathlib import Path

from typing import Optional

from .adapters import OTHER_BRANCH, REPO_ID, GitAdapter, OakAdapter, Server, payload

from .readers import OakGraph

FIXTURE_VERSION = "2"

@dataclass

class Fixture:

    subject: str

    kind: str

    op: str

    root: Path

    port: Optional[int]

    branch: str

    meta: dict = field(default_factory=dict)

    @property

    def pristine(self) -> Path:

        return self.root / "pristine"

    def save(self) -> None:

        (self.root / "meta.json").write_text(json.dumps(self.meta, indent=2, sort_keys=True))

def _oak_branch(repo: Path) -> str:

    with OakGraph(repo / ".oak" / "oak.db") as g:

        branch = g.metadata("current_branch")

    if not branch:

        raise RuntimeError("fixture: no current branch after first push")

    return branch

def build_oak(oak_bin: str, op: str, root: Path, port: int) -> Fixture:

    if root.exists():

        shutil.rmtree(root)

    base = root / "pristine"

    client, other, srv = base / "client", base / "other", base / "srv"

    for d in (client, srv):

        d.mkdir(parents=True)

    adapter = OakAdapter(oak_bin, base / "home")

    server = Server(oak_bin, srv, port, root / "fixture-serve.log").start()

    try:

        url = server.url

        adapter.must([oak_bin, "init", "."], client)

        payload(client, "base")

        adapter.must([oak_bin, "commit"], client)

        adapter.must([oak_bin, "push", "--repo", REPO_ID, "-r", url], client)

        branch = _oak_branch(client)

        meta: dict = {"url": url, "repo_id": REPO_ID}

        if op == "commit":

            payload(client, "new")

            payload(client, "added", count=20, start=200, prefix="n")

        elif op == "push":

            payload(client, "new")

            adapter.must([oak_bin, "commit"], client)

        elif op in ("pull_ff", "pull_diverged"):

            adapter.must([oak_bin, "clone", REPO_ID, str(other), "-r", url, "--branch", branch], base)

            payload(other, "theirs", count=100)

            payload(other, "theirs-new", count=50, start=300, prefix="t")

            adapter.must([oak_bin, "commit"], other)

            adapter.must([oak_bin, "push"], other)

            if op == "pull_diverged":

                (client / "local.txt").write_text("local unpushed work\n")

                payload(client, "mine", count=50, start=150)

                adapter.must([oak_bin, "commit"], client)

        elif op == "switch":

            adapter.must([oak_bin, "switch", "-c", OTHER_BRANCH], client)

            payload(client, "side")

            payload(client, "side-new", count=50, start=400, prefix="s")

            adapter.must([oak_bin, "commit"], client)

            adapter.must([oak_bin, "switch", branch], client)

            meta["target"] = OTHER_BRANCH

        elif op == "clone":

            pass

        else:

            raise KeyError(op)

        with OakGraph(client / ".oak" / "oak.db") as g:

            meta["pre_local_heads"] = sorted(g.ref_heads())

            meta["pre_head"] = g.metadata("head")

        with OakGraph(server.db()) as g:

            meta["pre_server_heads"] = g.branch_heads()

    finally:

        server.stop()

    if other.exists():

        shutil.rmtree(other)

    shutil.rmtree(base / "home", ignore_errors=True)

    fixture = Fixture("oak_installed", "oak", op, root, port, branch, meta)

    fixture.save()

    return fixture

def build_git(git_bin: str, op: str, root: Path, port: Optional[int] = None) -> Fixture:

    if root.exists():

        shutil.rmtree(root)

    base = root / "pristine"

    client, other, srv = base / "client", base / "other", base / "srv"

    client.mkdir(parents=True)

    srv.mkdir(parents=True)

    adapter = GitAdapter(git_bin, base / "home")

    g = git_bin

    adapter.must([g, "init", "-q", "--bare", "-b", "main", "remote.git"], srv)

    adapter.must([g, "config", "http.receivepack", "true"], srv / "remote.git")

    adapter.must([g, "init", "-q", "-b", "main", "."], client)

    payload(client, "base")

    adapter.must([g, "add", "-A"], client)

    adapter.must([g, "commit", "-q", "-m", "base"], client)

    adapter.must([g, "remote", "add", "origin", "../srv/remote.git"], client)

    adapter.must([g, "push", "-q", "-u", "origin", "main"], client)

    branch = "main"

    meta: dict = {"url": "srv/remote.git", "repo_id": "remote.git"}

    if op == "commit":

        payload(client, "new")

        payload(client, "added", count=20, start=200, prefix="n")

    elif op == "push":

        payload(client, "new")

        adapter.must([g, "commit", "-q", "-am", "new"], client)

    elif op in ("pull_ff", "pull_diverged"):

        adapter.must([g, "clone", "-q", "srv/remote.git", "other"], base)

        payload(other, "theirs", count=100)

        payload(other, "theirs-new", count=50, start=300, prefix="t")

        adapter.must([g, "add", "-A"], other)

        adapter.must([g, "commit", "-q", "-m", "theirs"], other)

        adapter.must([g, "push", "-q", "origin", "main"], other)

        if op == "pull_diverged":

            (client / "local.txt").write_text("local unpushed work\n")

            payload(client, "mine", count=50, start=150)

            adapter.must([g, "add", "-A"], client)

            adapter.must([g, "commit", "-q", "-m", "mine"], client)

    elif op in ("switch", "merge_local"):

        adapter.must([g, "switch", "-q", "-c", OTHER_BRANCH], client)

        if op == "switch":

            payload(client, "side")

        else:

            payload(client, "side", count=100, start=100)

        payload(client, "side-new", count=50, start=400, prefix="s")

        adapter.must([g, "add", "-A"], client)

        adapter.must([g, "commit", "-q", "-m", "side"], client)

        adapter.must([g, "switch", "-q", "main"], client)

        if op == "merge_local":

            payload(client, "mainside", count=50)

            adapter.must([g, "commit", "-q", "-am", "mainside"], client)

        meta["target"] = OTHER_BRANCH

    elif op == "clone":

        pass

    else:

        raise KeyError(op)

    oracle = adapter.oracle

    client_refs = oracle.refs(client)

    meta["pre_local_heads"] = sorted(set(client_refs.values()))

    meta["pre_head"] = client_refs.get("HEAD")

    meta["pre_server_heads"] = {k.removeprefix("refs/heads/"): v for k, v in oracle.refs(srv / "remote.git").items()

                                if k.startswith("refs/heads/")}

    if other.exists():

        shutil.rmtree(other)

    shutil.rmtree(base / "home", ignore_errors=True)

    fixture = Fixture("git", "git", op, root, port, branch, meta)

    fixture.save()

    return fixture