"""Keeps the match and emulator results that the Logbook's exact and verified tiers come from current, so nobody has to
remember to rerun them:

  match       the whole-program check of main ([reverse] ltcg: `ltcg.py check --build --decomp <main> --json`),
              written to [reverse] match_results; when main's HEAD has moved, at most every match_every_minutes.
  behaviour   the emulator over every readable file ([reverse] diffrun_command: `diffrun.py --readable --jobs 4
              --json`), written to [reverse] diffrun_results, its printout to readable.txt beside it; when main's
              HEAD has moved, at most every behaviour_every_hours and only inside behaviour_window (local hours).

Configured per project in the [logbook] table (main is [logbook] decomp):
    results_refresh = true          off unless set
    match_every_minutes = 60
    behaviour_every_hours = 12
    behaviour_window = "01-06"      from 01:00 to 06:00 local time; "" for any hour

One run at a time (the server runs one thread for every project), at the lowest process priority, into a .partial file
that replaces the results only once it is complete. The match run holds the same per-checkout lock as re_match_program,
so it waits its turn behind any other whole-program build of main.

State (per job: the commit, start and finish of the last run, its counts and error; a run in progress) is kept in the
logbook folder as results.json, so a restarted server neither repeats a run nor starts a second one beside a run its
predecessor left going (that run's output is adopted when it finishes). `harbor logbook results --job match|behaviour`
asks the server for a run now, whatever the schedule; it is a file, refresh-<job>.request, in the same folder."""
import datetime
import json
import os
import subprocess
import sys
import tempfile
import time
import traceback
from pathlib import Path

from . import logbook

JOBS = ("match", "behaviour")
RESULTS_KEY = {"match": "match_results", "behaviour": "diffrun_results"}
DEFAULTS = {"results_refresh": False, "match_every_minutes": 60, "behaviour_every_hours": 12,
            "behaviour_window": "01-06"}
TIMEOUT = {"match": 2 * 3600, "behaviour": 8 * 3600}     # generous: the runs are at idle priority on a busy machine
TICK = 120                                               # seconds between looks
START_DELAY = 60                                         # let a restarted server settle first
STATE = "results.json"


# ---------------------------------------------------------------------------------------------- configuration
def settings(project):
    lb = getattr(project, "logbook", None) or {}
    return {k: lb.get(k, v) for k, v in DEFAULTS.items()}


def window(text):
    """"01-06" -> (1, 6): from 01:00 up to 06:00. "22-04" wraps past midnight. ""/None -> None (any hour)."""
    text = str(text or "").strip()
    if not text or text.lower() in ("any", "always"):
        return None
    start, end = (int(part) for part in text.split("-", 1))
    if not (0 <= start <= 24 and 0 <= end <= 24):
        raise ValueError(f"behaviour_window hours must be 0-24: {text!r}")
    return start, end


def in_window(span, hour):
    if span is None:
        return True
    start, end = span
    if start == end:
        return True
    return start <= hour < end if start < end else hour >= start or hour < end


def configured(project, job):
    """What a job needs from the project, or None when it cannot run here."""
    rev = project.reverse or {}
    lb = getattr(project, "logbook", None) or {}
    if not lb.get("decomp") or not rev.get(RESULTS_KEY[job]):
        return None
    if job == "match" and rev.get("ltcg"):
        return {"script": rev["ltcg"], "results": rev["match_results"]}
    if job == "behaviour" and rev.get("diffrun_command"):
        command = rev["diffrun_command"]
        return {"command": command if isinstance(command, list) else [command], "results": rev["diffrun_results"]}
    return None


# ---------------------------------------------------------------------------------------------- state
def _folder(project):
    return logbook.folder(project)


def load_state(project):
    path = _folder(project) / STATE
    try:
        state = json.loads(path.read_text(encoding="utf-8")) if path.exists() else {}
    except (OSError, ValueError):
        state = {}
    state.setdefault("jobs", {})
    return state


def save_state(project, state):
    path = _folder(project) / STATE
    partial = path.with_name(path.name + ".partial")
    partial.write_text(json.dumps(state, indent=1), encoding="utf-8")
    os.replace(partial, path)


def request(project, job):
    """Ask the server's refresher for a run of `job` at its next look, whatever the schedule."""
    if job not in JOBS:
        raise ValueError(f"job is one of {', '.join(JOBS)}")
    path = _folder(project) / f"refresh-{job}.request"
    path.write_text(_iso(time.time()), encoding="utf-8")
    return {"requested": job, "file": str(path)}


def _requested(project):
    return {job for job in JOBS if (_folder(project) / f"refresh-{job}.request").exists()}


def _clear_request(project, job):
    try:
        (_folder(project) / f"refresh-{job}.request").unlink()
    except FileNotFoundError:
        pass


def _iso(ts):
    return datetime.datetime.fromtimestamp(ts, datetime.timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")


# ---------------------------------------------------------------------------------------------- the decision
def due(cfg, state, job, head, now, hour, requested=()):
    """(True, why) when `job` should run now; (False, why not) otherwise. Pure: the tests drive it directly."""
    if job in requested:
        return True, "requested"
    if not cfg.get("results_refresh"):
        return False, "results_refresh is off"
    last = state.get("jobs", {}).get(job, {})
    if last.get("head") == head:
        return False, "already at main's HEAD"
    if job == "match":
        every = float(cfg.get("match_every_minutes", 60)) * 60
    else:
        every = float(cfg.get("behaviour_every_hours", 12)) * 3600
    if last.get("started_ts") and now - last["started_ts"] < every:
        return False, f"last run started {int((now - last['started_ts']) / 60)} min ago"
    if job == "behaviour" and not in_window(window(cfg.get("behaviour_window")), hour):
        return False, f"outside behaviour_window {cfg.get('behaviour_window')}"
    return True, "main moved"


def choose(cfg, state, head, now, hour, requested=(), available=JOBS):
    """The one job to run now (the match first: it is quicker and more often due), or (None, reasons)."""
    reasons = {}
    for job in JOBS:
        if job not in available:
            reasons[job] = "not configured"
            continue
        ok, why = due(cfg, state, job, head, now, hour, requested)
        if ok:
            return job, why
        reasons[job] = why
    return None, reasons


# ---------------------------------------------------------------------------------------------- running
def _head(project):
    from .logbook_auto import _git
    return _git(project.logbook["decomp"], "rev-parse", "HEAD").strip()


def _spawn(argv, cwd, stdout, stderr):
    flags = 0
    if os.name == "nt":
        flags = subprocess.IDLE_PRIORITY_CLASS | subprocess.CREATE_NO_WINDOW   # children (cl.exe) inherit idle
    env = dict(os.environ, PYTHONIOENCODING="utf-8")
    return subprocess.Popen(argv, cwd=str(cwd), stdin=subprocess.DEVNULL, stdout=stdout, stderr=stderr, env=env,
                            creationflags=flags)


def _kill_tree(pid):
    if os.name == "nt":
        subprocess.run(["taskkill", "/PID", str(pid), "/T", "/F"], capture_output=True,
                       creationflags=getattr(subprocess, "CREATE_NO_WINDOW", 0))
    else:
        try:
            os.kill(pid, 9)
        except OSError:
            pass


def _alive(pid):
    from .reverse import pid_alive
    return bool(pid) and pid_alive(pid)


def _paths(project, job):
    target = Path(configured(project, job)["results"])
    paths = {"target": target, "partial": target.with_name(target.name + ".partial"),
             "log": _folder(project) / f"{job}.log"}
    if job == "behaviour":
        paths["text"] = target.with_suffix(".txt")
        paths["text_partial"] = target.with_suffix(".txt.partial")
    return paths


def _argv(project, job, out):
    need = configured(project, job)
    if job == "match":
        script = Path(need["script"])
        return [sys.executable, "-B", str(script), "check", "--build", "--decomp",
                str(Path(project.logbook["decomp"])), "--json", str(out)], script.parent
    command = [str(c) for c in need["command"]]
    return command + ["--readable", "--jobs", "4", "--json", str(out)], Path(command[-1]).parent


def _match_lock(project):
    """The lock re_match_program holds around a whole-program build of main (harbor.reverse.match_program)."""
    from .reverse import _exclusive
    rev = project.reverse or {}
    return _exclusive(Path(rev.get("debugger_temp") or tempfile.gettempdir()) / "ltcg-main.lock", wait_seconds=0)


def _counts(rows, field):
    counts = {}
    for r in rows:
        counts[str(r.get(field))] = counts.get(str(r.get(field)), 0) + 1
    return counts


def _complete(project, state, run, now, returncode=None):
    """Move a finished run's output into place, or record why it failed. Clears state['running']."""
    job, paths = run["job"], _paths(project, run["job"])
    last = dict(state["jobs"].get(job, {}))
    last.update(started_ts=run["started_ts"], started=_iso(run["started_ts"]), finished=_iso(now))
    try:
        partial = paths["partial"]
        text = partial.read_text(encoding="utf-8") if partial.exists() else ""
        if not text.strip():
            ended = "the run was interrupted" if returncode is None else \
                returncode if isinstance(returncode, str) else f"exit code {returncode}"
            raise RuntimeError(f"no results were written ({ended}); see {paths['log']}")
        rows = json.loads(text)
        if not isinstance(rows, list) or not rows:
            raise RuntimeError("the results file is empty")
        os.replace(partial, paths["target"])
        if job == "behaviour" and paths["text_partial"].exists():
            os.replace(paths["text_partial"], paths["text"])
        last.update(head=run["head"], ok=True, error=None, functions=len(rows),
                    counts=_counts(rows, "status" if job == "match" else "verdict"),
                    results_mtime_ns=paths["target"].stat().st_mtime_ns)
    except (OSError, ValueError, RuntimeError) as error:
        last.update(ok=False, error=str(error)[:500])
    state["jobs"][job] = last
    state.pop("running", None)
    save_state(project, state)
    return {"job": job, "ok": last["ok"], "head": run["head"][:8], **({"error": last["error"]} if not last["ok"] else {})}


def run_job(project, state, job, head, now, reason=""):
    paths = _paths(project, job)
    argv, cwd = _argv(project, job, paths["partial"])
    for stale in [paths["partial"]] + ([paths["text_partial"]] if job == "behaviour" else []):
        if stale.exists():
            stale.write_bytes(b"")                     # a leftover of an interrupted run is never taken for this one
    run = {"job": job, "pid": None, "head": head, "started_ts": now, "reason": reason}
    clock = time.monotonic()
    returncode = None
    with open(paths["log"], "wb") as log:
        stdout = open(paths["text_partial"], "wb") if job == "behaviour" else log
        try:
            log.write(f"{_iso(now)} {job} at {head[:8]} ({reason}): {' '.join(argv)}\n".encode("utf-8"))
            log.flush()
            proc = _spawn(argv, cwd, stdout, log if job == "behaviour" else subprocess.STDOUT)
            run["pid"] = proc.pid
            state["running"] = {**run, "started": _iso(now)}
            save_state(project, state)
            try:
                returncode = proc.wait(timeout=TIMEOUT[job])
            except subprocess.TimeoutExpired:
                _kill_tree(proc.pid)
                proc.wait()
                returncode = f"timed out after {TIMEOUT[job] // 60} min"
        except OSError as error:
            returncode = f"could not start: {error}"
        finally:
            if stdout is not log:
                stdout.close()
    return _complete(project, state, run, now + (time.monotonic() - clock), returncode)


def tick(project, now=None, hour=None):
    """One look: finish off a run an earlier server left, then start the job that is due (and wait for it)."""
    now = time.time() if now is None else now
    hour = datetime.datetime.now().hour if hour is None else hour
    available = [job for job in JOBS if configured(project, job)]
    if not available:
        return {"idle": "not configured"}
    state = load_state(project)
    running = state.get("running")
    if running:
        if _alive(running.get("pid")) and now - running.get("started_ts", 0) < TIMEOUT.get(running.get("job"), 0):
            return {"busy": running["job"], "pid": running["pid"]}
        return {"adopted": _complete(project, state, running, now)}
    requested = _requested(project)
    if not requested and not settings(project).get("results_refresh"):
        return {"idle": "results_refresh is off"}
    head = _head(project)
    job, why = choose(settings(project), state, head, now, hour, requested, available)
    if not job:
        return {"idle": why, "head": head[:8]}
    if job == "match":
        from .util import HarborError
        try:
            with _match_lock(project):
                _clear_request(project, job)
                return run_job(project, state, job, head, now, why)
        except HarborError:
            return {"waiting": "another whole-program build of main holds the lock"}
    _clear_request(project, job)
    return run_job(project, state, job, head, now, why)


# ---------------------------------------------------------------------------------------------- reading
def freshness(project):
    """For the progress view: which commit the exact and verified tiers are from, and how old they are."""
    state = load_state(project)
    out = {}
    for job in JOBS:
        need = configured(project, job)
        target = Path(need["results"]) if need else Path((project.reverse or {}).get(RESULTS_KEY[job]) or "")
        last = state["jobs"].get(job, {})
        try:
            mtime_ns = target.stat().st_mtime_ns if str(target) not in ("", ".") else None
        except OSError:
            mtime_ns = None
        if mtime_ns is None:
            out[job] = None
            continue
        ours = last.get("ok") and last.get("results_mtime_ns") == mtime_ns
        out[job] = {"sha": last["head"][:7] if ours else None,
                    "at": last.get("finished") if ours else _iso(mtime_ns / 1e9),
                    "error": last.get("error") if last.get("ok") is False else None}
    running = state.get("running")
    out["running"] = {"job": running["job"], "started": running.get("started")} if running else None
    out["enabled"] = bool(settings(project).get("results_refresh"))
    return out


def status(project, now=None, hour=None):
    """For `harbor logbook results`: the state plus what the next look would do."""
    now = time.time() if now is None else now
    hour = datetime.datetime.now().hour if hour is None else hour
    state = load_state(project)
    available = [job for job in JOBS if configured(project, job)]
    try:
        head = _head(project) if available else ""
    except RuntimeError:
        head = ""
    nxt = {job: due(settings(project), state, job, head, now, hour, _requested(project))
           for job in available}
    return {"settings": settings(project), "head": head[:8], "jobs": state["jobs"], "running": state.get("running"),
            "requested": sorted(_requested(project)),
            "next": {job: {"due": ok, "why": why} for job, (ok, why) in nxt.items()},
            "state_file": str(_folder(project) / STATE)}


def loop(registry):
    """Server thread: one look every two minutes at every project (results_refresh on, or a run requested)."""
    time.sleep(START_DELAY)
    while True:
        for name in registry.names():
            try:
                h, _ = registry.get(name)
                tick(h.project)
            except Exception:
                traceback.print_exc()
        time.sleep(TICK)