"""Avocet — FastAPI REST layer.

JSONL read/write helpers and FastAPI app instance.
Endpoints and static file serving are added in subsequent tasks.
"""
from __future__ import annotations

import hashlib
import json
import yaml
from pathlib import Path

from datetime import datetime, timezone

from fastapi import FastAPI, HTTPException, Query
from pydantic import BaseModel

_ROOT = Path(__file__).parent.parent
_DATA_DIR: Path = _ROOT / "data"   # overridable in tests via set_data_dir()
_CONFIG_DIR: Path | None = None    # None = use real path


def set_data_dir(path: Path) -> None:
    """Override data directory — used by tests."""
    global _DATA_DIR
    _DATA_DIR = path


def set_config_dir(path: Path | None) -> None:
    """Override config directory — used by tests."""
    global _CONFIG_DIR
    _CONFIG_DIR = path


def _config_file() -> Path:
    if _CONFIG_DIR is not None:
        return _CONFIG_DIR / "label_tool.yaml"
    return _ROOT / "config" / "label_tool.yaml"


def reset_last_action() -> None:
    """Reset undo state — used by tests."""
    global _last_action
    _last_action = None


def _queue_file() -> Path:
    return _DATA_DIR / "email_label_queue.jsonl"


def _score_file() -> Path:
    return _DATA_DIR / "email_score.jsonl"


def _discarded_file() -> Path:
    return _DATA_DIR / "discarded.jsonl"


def _read_jsonl(path: Path) -> list[dict]:
    if not path.exists():
        return []
    lines = path.read_text(encoding="utf-8").splitlines()
    return [json.loads(l) for l in lines if l.strip()]


def _write_jsonl(path: Path, records: list[dict]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    text = "\n".join(json.dumps(r, ensure_ascii=False) for r in records)
    path.write_text(text + "\n" if records else "", encoding="utf-8")


def _append_jsonl(path: Path, record: dict) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("a", encoding="utf-8") as f:
        f.write(json.dumps(record, ensure_ascii=False) + "\n")


def _item_id(item: dict) -> str:
    """Stable content-hash ID — matches label_tool.py _entry_key dedup logic."""
    key = (item.get("subject", "") + (item.get("body", "") or "")[:100])
    return hashlib.md5(key.encode("utf-8", errors="replace")).hexdigest()


def _normalize(item: dict) -> dict:
    """Normalize JSONL item to the Vue frontend schema.

    label_tool.py stores: subject, body, from_addr, date, account (no id).
    The Vue app expects: id, subject, body, from, date, source.
    Both old (from_addr/account) and new (from/source) field names are handled.
    """
    return {
        "id":      item.get("id") or _item_id(item),
        "subject": item.get("subject", ""),
        "body":    item.get("body", ""),
        "from":    item.get("from") or item.get("from_addr", ""),
        "date":    item.get("date", ""),
        "source":  item.get("source") or item.get("account", ""),
    }


app = FastAPI(title="Avocet API")

# In-memory last-action store (single user, local tool — in-memory is fine)
_last_action: dict | None = None


@app.get("/api/queue")
def get_queue(limit: int = Query(default=10, ge=1, le=50)):
    items = _read_jsonl(_queue_file())
    return {"items": [_normalize(x) for x in items[:limit]], "total": len(items)}


class LabelRequest(BaseModel):
    id: str
    label: str


@app.post("/api/label")
def post_label(req: LabelRequest):
    global _last_action
    items = _read_jsonl(_queue_file())
    match = next((x for x in items if _normalize(x)["id"] == req.id), None)
    if not match:
        raise HTTPException(404, f"Item {req.id!r} not found in queue")
    record = {**match, "label": req.label,
              "labeled_at": datetime.now(timezone.utc).isoformat()}
    _append_jsonl(_score_file(), record)
    _write_jsonl(_queue_file(), [x for x in items if _normalize(x)["id"] != req.id])
    _last_action = {"type": "label", "item": match, "label": req.label}
    return {"ok": True}


class SkipRequest(BaseModel):
    id: str


@app.post("/api/skip")
def post_skip(req: SkipRequest):
    global _last_action
    items = _read_jsonl(_queue_file())
    match = next((x for x in items if _normalize(x)["id"] == req.id), None)
    if not match:
        raise HTTPException(404, f"Item {req.id!r} not found in queue")
    reordered = [x for x in items if _normalize(x)["id"] != req.id] + [match]
    _write_jsonl(_queue_file(), reordered)
    _last_action = {"type": "skip", "item": match}
    return {"ok": True}


class DiscardRequest(BaseModel):
    id: str


@app.post("/api/discard")
def post_discard(req: DiscardRequest):
    global _last_action
    items = _read_jsonl(_queue_file())
    match = next((x for x in items if _normalize(x)["id"] == req.id), None)
    if not match:
        raise HTTPException(404, f"Item {req.id!r} not found in queue")
    record = {**match, "label": "__discarded__",
              "discarded_at": datetime.now(timezone.utc).isoformat()}
    _append_jsonl(_discarded_file(), record)
    _write_jsonl(_queue_file(), [x for x in items if _normalize(x)["id"] != req.id])
    _last_action = {"type": "discard", "item": match}
    return {"ok": True}


@app.delete("/api/label/undo")
def delete_undo():
    global _last_action
    if not _last_action:
        raise HTTPException(404, "No action to undo")
    action = _last_action
    item = action["item"]   # always the original clean queue item

    # Perform file operations FIRST — only clear _last_action on success
    if action["type"] == "label":
        records = _read_jsonl(_score_file())
        if not records:
            raise HTTPException(409, "Score file is empty — cannot undo label")
        _write_jsonl(_score_file(), records[:-1])
        items = _read_jsonl(_queue_file())
        _write_jsonl(_queue_file(), [item] + items)
    elif action["type"] == "discard":
        records = _read_jsonl(_discarded_file())
        if not records:
            raise HTTPException(409, "Discarded file is empty — cannot undo discard")
        _write_jsonl(_discarded_file(), records[:-1])
        items = _read_jsonl(_queue_file())
        _write_jsonl(_queue_file(), [item] + items)
    elif action["type"] == "skip":
        items = _read_jsonl(_queue_file())
        item_id = _normalize(item)["id"]
        items = [item] + [x for x in items if _normalize(x)["id"] != item_id]
        _write_jsonl(_queue_file(), items)

    # Clear AFTER all file operations succeed
    _last_action = None
    return {"undone": {"type": action["type"], "item": _normalize(item)}}


# Label metadata — 10 labels matching label_tool.py
_LABEL_META = [
    {"name": "interview_scheduled", "emoji": "\U0001f4c5",  "color": "#4CAF50", "key": "1"},
    {"name": "offer_received",      "emoji": "\U0001f389",  "color": "#2196F3", "key": "2"},
    {"name": "rejected",            "emoji": "\u274c",      "color": "#F44336", "key": "3"},
    {"name": "positive_response",   "emoji": "\U0001f44d",  "color": "#FF9800", "key": "4"},
    {"name": "survey_received",     "emoji": "\U0001f4cb",  "color": "#9C27B0", "key": "5"},
    {"name": "neutral",             "emoji": "\u2b1c",      "color": "#607D8B", "key": "6"},
    {"name": "event_rescheduled",   "emoji": "\U0001f504",  "color": "#FF5722", "key": "7"},
    {"name": "digest",              "emoji": "\U0001f4f0",  "color": "#00BCD4", "key": "8"},
    {"name": "new_lead",            "emoji": "\U0001f91d",  "color": "#009688", "key": "9"},
    {"name": "hired",               "emoji": "\U0001f38a",  "color": "#FFC107", "key": "h"},
]


@app.get("/api/config/labels")
def get_labels():
    return _LABEL_META


@app.get("/api/config")
def get_config():
    f = _config_file()
    if not f.exists():
        return {"accounts": [], "max_per_account": 500}
    raw = yaml.safe_load(f.read_text(encoding="utf-8")) or {}
    return {"accounts": raw.get("accounts", []), "max_per_account": raw.get("max_per_account", 500)}


class ConfigPayload(BaseModel):
    accounts: list[dict]
    max_per_account: int = 500


@app.post("/api/config")
def post_config(payload: ConfigPayload):
    f = _config_file()
    f.parent.mkdir(parents=True, exist_ok=True)
    tmp = f.with_suffix(".tmp")
    tmp.write_text(yaml.dump(payload.model_dump(), allow_unicode=True, sort_keys=False),
                   encoding="utf-8")
    tmp.rename(f)
    return {"ok": True}


# Static SPA — MUST be last (catches all unmatched paths)
_DIST = _ROOT / "web" / "dist"
if _DIST.exists():
    from fastapi.responses import FileResponse
    from fastapi.staticfiles import StaticFiles

    # Serve index.html with no-cache so browsers always fetch fresh HTML after rebuilds.
    # Hashed assets (/assets/index-abc123.js) can be cached forever — they change names
    # when content changes (standard Vite cache-busting strategy).
    _NO_CACHE = {"Cache-Control": "no-cache, no-store, must-revalidate", "Pragma": "no-cache"}

    @app.get("/")
    def get_spa_root():
        return FileResponse(str(_DIST / "index.html"), headers=_NO_CACHE)

    app.mount("/", StaticFiles(directory=str(_DIST), html=True), name="spa")