"""
Reconciliation (item vs price tag) and the first compliance rule family.

Two pure layers, no I/O:

- `reconcile()` compares one accepted identity with its tag and the catalog entry,
  and publishes a state plus the individual signals. It never changes the product
  identity: a disagreement is a second opinion, displayed next to the first.
- `evaluate_compliance()` turns settled evidence into findings. Every rule fails
  closed on evidence quality: a row whose tags are merely unreadable produces a
  capture hint, never a violation.
"""

from __future__ import annotations

import os
import re
import sys
import unicodedata
from dataclasses import dataclass, field
from typing import Any, Dict, Iterable, List, Optional, Sequence, Tuple

current_dir = os.path.dirname(os.path.abspath(__file__))
if current_dir not in sys.path:
    sys.path.insert(0, current_dir)

from tags import TAG_STATE_ABSENT, TAG_STATE_READABLE, TAG_STATE_UNREADABLE  # noqa: E402

RECONCILED_CONFIRMED = "confirmed"
RECONCILED_MISMATCH = "mismatch"
RECONCILED_UNVERIFIED = "unverified"
RECONCILED_NO_TAG = "no_tag"
RECONCILED_TAG_ONLY = "tag_only"

RULE_MISSING_TAG = "missing_price_tag"
RULE_MISSING_TAG_GROUP = "missing_tag_group"
RULE_ORPHAN_TAG = "orphan_tag"
RULE_PRICE_MISMATCH = "price_mismatch"
RULE_DUPLICATE_TAG = "duplicate_tag"
RULE_UNREADABLE_TAGS = "unreadable_tags"

NAME_MATCH_THRESHOLD = 0.4
GROUP_MIN_FACINGS = 3
STABILITY_FRAMES = 3
STABILITY_WINDOW = 5


# ---------------------------------------------------------------------------
# text matching
# ---------------------------------------------------------------------------


def normalize_name(text: Optional[str]) -> str:
    if not text:
        return ""
    text = unicodedata.normalize("NFKC", text)
    text = re.sub(r"<[^>]*>", "", text)
    text = re.sub(r"[\s・、。,.\-–—_/]+", "", text)
    return text.lower()


def longest_common_substring_ratio(a: str, b: str) -> float:
    """Length of the longest common substring over the shorter string."""
    if not a or not b:
        return 0.0
    shorter, longer = (a, b) if len(a) <= len(b) else (b, a)
    best = 0
    for start in range(len(shorter)):
        for end in range(start + best + 1, len(shorter) + 1):
            if shorter[start:end] in longer:
                best = end - start
            else:
                break
    return best / len(shorter)


# ---------------------------------------------------------------------------
# reconciliation
# ---------------------------------------------------------------------------


@dataclass
class Signal:
    kind: str          # "jan" | "name" | "price"
    agrees: bool
    item: Any
    tag: Any
    note: Optional[str] = None

    def as_dict(self) -> Dict[str, Any]:
        payload = {"kind": self.kind, "agrees": self.agrees, "item": self.item, "tag": self.tag}
        if self.note:
            payload["note"] = self.note
        return payload


def reconcile(
    identity: Optional[Dict[str, Any]],
    tag: Optional[Dict[str, Any]],
    product: Optional[Dict[str, Any]],
) -> Optional[Dict[str, Any]]:
    """Compare one facing with its tag.

    Returns None when there is nothing to reconcile (no accepted identity and no
    readable tag). A tag with no product above it is `tag_only`.
    """
    identity_state = (identity or {}).get("state")
    tag_state = (tag or {}).get("state", TAG_STATE_ABSENT)
    accepted = identity_state == "recognized"
    readable_tag = tag_state == TAG_STATE_READABLE

    if not accepted and not readable_tag:
        return None

    if accepted and tag_state == TAG_STATE_ABSENT:
        return {"state": RECONCILED_NO_TAG, "signals": [], "message": None}
    if accepted and tag_state == TAG_STATE_UNREADABLE:
        return {
            "state": RECONCILED_UNVERIFIED,
            "signals": [],
            "message": "tag found but its text was not read",
        }
    if not accepted and readable_tag:
        return {"state": RECONCILED_TAG_ONLY, "signals": [], "message": None}

    signals: List[Signal] = []

    # JAN is the only exact signal; a checksummed barcode is not a guess.
    item_jan = str((product or {}).get("jan") or "").strip()
    tag_jan = str((tag or {}).get("jan") or "").strip()
    if item_jan and tag_jan:
        signals.append(Signal("jan", item_jan == tag_jan, item_jan, tag_jan))

    item_name = normalize_name((product or {}).get("product_name"))
    tag_name = normalize_name((tag or {}).get("name"))
    if item_name and tag_name:
        ratio = longest_common_substring_ratio(item_name, tag_name)
        signals.append(
            Signal("name", ratio >= NAME_MATCH_THRESHOLD, item_name[:32], tag_name[:32],
                   note=f"match {ratio:.2f}")
        )

    item_price = (product or {}).get("price")
    tag_price = (tag or {}).get("price")
    tag_regular = (tag or {}).get("regular_price")
    if item_price is not None and (tag_price is not None or tag_regular is not None):
        candidates = [value for value in (tag_price, tag_regular) if value is not None]
        agrees = any(abs(float(item_price) - float(value)) < 0.5 for value in candidates)
        signals.append(Signal("price", agrees, item_price, tag_price if tag_price is not None else tag_regular))

    if not signals:
        return {
            "state": RECONCILED_UNVERIFIED,
            "signals": [],
            "message": "tag read, but nothing comparable in the catalog",
        }

    if any(signal.kind == "jan" for signal in signals):
        decided = [signal for signal in signals if signal.kind == "jan"][0]
        state = RECONCILED_CONFIRMED if decided.agrees else RECONCILED_MISMATCH
    elif any(signal.agrees for signal in signals):
        state = RECONCILED_CONFIRMED
    elif all(not signal.agrees for signal in signals):
        state = RECONCILED_MISMATCH
    else:
        state = RECONCILED_UNVERIFIED

    message = None
    if state == RECONCILED_MISMATCH:
        price_signal = next((signal for signal in signals if signal.kind == "price"), None)
        name_signal = next((signal for signal in signals if signal.kind == "name"), None)
        if price_signal is not None:
            message = f"tag says {price_signal.tag}, catalog says {price_signal.item}"
        elif name_signal is not None:
            message = "tag name does not match the catalog entry"
    return {"state": state, "signals": [signal.as_dict() for signal in signals], "message": message}


# ---------------------------------------------------------------------------
# compliance
# ---------------------------------------------------------------------------


@dataclass
class ComplianceSettings:
    group_min_facings: int = GROUP_MIN_FACINGS
    stability_frames: int = STABILITY_FRAMES
    stability_window: int = STABILITY_WINDOW


@dataclass
class Finding:
    rule: str
    severity: str                 # "violation" | "hint"
    row_index: Optional[int]
    box: List[int]
    count: int = 1
    skus: List[str] = field(default_factory=list)
    detail: Optional[str] = None

    def key(self) -> Tuple[Any, ...]:
        return (self.rule, self.row_index, self.box[0] // 32, self.box[1] // 32, self.count)

    def as_dict(self) -> Dict[str, Any]:
        payload = {
            "rule": self.rule,
            "severity": self.severity,
            "row_index": self.row_index,
            "box": list(self.box),
            "count": self.count,
            "skus": list(self.skus),
        }
        if self.detail:
            payload["detail"] = self.detail
        return payload


class ComplianceTracker:
    """Keeps findings only while they persist, so the UI never flickers."""

    def __init__(self, settings: Optional[ComplianceSettings] = None):
        self.settings = settings or ComplianceSettings()
        self._history: List[set] = []

    def update(self, findings: Sequence[Finding]) -> List[Finding]:
        current = {finding.key(): finding for finding in findings}
        self._history.append(set(current))
        if len(self._history) > self.settings.stability_window:
            self._history.pop(0)
        stable: List[Finding] = []
        for key, finding in current.items():
            seen = sum(1 for frame in self._history if key in frame)
            if seen >= self.settings.stability_frames:
                stable.append(finding)
        return stable

    def reset(self) -> None:
        self._history.clear()


def evaluate_compliance(
    tracks: Sequence[Dict[str, Any]],
    tag_by_track: Dict[int, Dict[str, Any]],
    all_tags: Sequence[Dict[str, Any]],
    bands: Sequence[Any],
    reconciliations: Optional[Dict[int, Dict[str, Any]]] = None,
    settings: Optional[ComplianceSettings] = None,
) -> List[Finding]:
    """Findings from settled evidence. Rules with unreadable evidence stay silent.

    `tag_by_track` is the per-facing attachment; `all_tags` is every tag the pass
    found, so a tag nobody claimed can be reported as an orphan.
    """
    settings = settings or ComplianceSettings()
    findings: List[Finding] = []

    by_row: Dict[int, List[Dict[str, Any]]] = {}
    for track in tracks:
        row_index = _row_for(track.get("box") or track.get("raw_box"), bands)
        by_row.setdefault(row_index, []).append(track)

    for row_index, row_tracks in by_row.items():
        row_tracks.sort(key=lambda track: (track.get("box") or [0])[0])
        row_tags = [tag_by_track.get(int(track["track_id"]), {}) for track in row_tracks]
        readable = [tag for tag in row_tags if tag.get("state") == TAG_STATE_READABLE]
        if not readable:
            # Fail closed: nothing in this row could be read, so nothing can be
            # claimed about missing tags here. Report the capture problem instead.
            if any(tag.get("state") == TAG_STATE_UNREADABLE for tag in row_tags):
                findings.append(
                    Finding(
                        rule=RULE_UNREADABLE_TAGS,
                        severity="hint",
                        row_index=row_index,
                        box=_row_box(row_tracks),
                        count=len(row_tracks),
                        detail="move closer: the price tags in this row could not be read",
                    )
                )
            continue

        # missing_price_tag, per facing
        missing: List[Dict[str, Any]] = []
        for track, tag in zip(row_tracks, row_tags):
            if tag.get("state") == TAG_STATE_ABSENT:
                missing.append(track)
        for track in missing:
            findings.append(
                Finding(
                    rule=RULE_MISSING_TAG,
                    severity="violation",
                    row_index=row_index,
                    box=list(track.get("box") or track.get("raw_box") or [0, 0, 0, 0]),
                    count=1,
                    skus=[_sku_of(track)],
                )
            )

        # missing_tag_group: consecutive facings without a tag
        run: List[Dict[str, Any]] = []
        for track, tag in zip(row_tracks, row_tags):
            if tag.get("state") == TAG_STATE_ABSENT:
                run.append(track)
                continue
            if len(run) >= settings.group_min_facings:
                findings.append(_group_finding(row_index, run))
            run = []
        if len(run) >= settings.group_min_facings:
            findings.append(_group_finding(row_index, run))

    # price_mismatch from reconciliation
    for track in tracks:
        track_id = int(track["track_id"])
        reconciliation = (reconciliations or {}).get(track_id)
        if not reconciliation or reconciliation.get("state") != RECONCILED_MISMATCH:
            continue
        if not any(signal.get("kind") == "price" for signal in reconciliation.get("signals", [])):
            continue
        findings.append(
            Finding(
                rule=RULE_PRICE_MISMATCH,
                severity="violation",
                row_index=_row_for(track.get("box") or track.get("raw_box"), bands),
                box=list(track.get("box") or track.get("raw_box") or [0, 0, 0, 0]),
                count=1,
                skus=[_sku_of(track)],
                detail=reconciliation.get("message"),
            )
        )

    # orphan_tag: a readable tag that no facing claims (a tag with no product above
    # it is either an empty slot with a leftover tag or a mis-clustered read).
    attached_ids = {
        tag.get("id") for tag in tag_by_track.values() if tag.get("id")
    }
    for tag in all_tags:
        if tag.get("state") != TAG_STATE_READABLE or not tag.get("id"):
            continue
        if tag["id"] in attached_ids:
            continue
        findings.append(
            Finding(
                rule=RULE_ORPHAN_TAG,
                severity="violation",
                row_index=None,
                box=list(tag.get("box") or [0, 0, 0, 0]),
                count=1,
                detail="price tag with no product above it",
            )
        )

    return findings


def _group_finding(row_index: int, run: Sequence[Dict[str, Any]]) -> Finding:
    boxes = [track.get("box") or track.get("raw_box") or [0, 0, 0, 0] for track in run]
    x1 = min(box[0] for box in boxes)
    y1 = min(box[1] for box in boxes)
    x2 = max(box[2] for box in boxes)
    y2 = max(box[3] for box in boxes)
    return Finding(
        rule=RULE_MISSING_TAG_GROUP,
        severity="violation",
        row_index=row_index,
        box=[x1, y1, x2, y2],
        count=len(run),
        skus=[_sku_of(track) for track in run],
        detail=f"{len(run)} facings in a row without a price tag",
    )


def _row_box(tracks: Sequence[Dict[str, Any]]) -> List[int]:
    boxes = [track.get("box") or track.get("raw_box") or [0, 0, 0, 0] for track in tracks]
    return [
        min(box[0] for box in boxes),
        min(box[1] for box in boxes),
        max(box[2] for box in boxes),
        max(box[3] for box in boxes),
    ]


def _row_for(box: Optional[Sequence[int]], bands: Sequence[Any]) -> int:
    """Which rail band (i.e. row) a facing sits above."""
    if not box or not bands:
        return 0
    x_center = (box[0] + box[2]) / 2.0
    y_bottom = box[3]
    best_index = 0
    best_distance = None
    for band in bands:
        bx1, by1, bx2, by2 = band.box
        if not (bx1 - 40 <= x_center <= bx2 + 40):
            continue
        distance = abs(by1 - y_bottom)
        if best_distance is None or distance < best_distance:
            best_distance = distance
            best_index = band.row_index
    return best_index


def _sku_of(track: Dict[str, Any]) -> str:
    identity = track.get("identity") or {}
    return str(identity.get("sku_id") or "")


def summarize_findings(findings: Sequence[Finding]) -> Dict[str, Any]:
    by_rule: Dict[str, int] = {}
    for finding in findings:
        if finding.severity != "violation":
            continue
        by_rule[finding.rule] = by_rule.get(finding.rule, 0) + 1
    return {
        "violations": sum(by_rule.values()),
        "by_rule": by_rule,
        "hints": [finding.as_dict() for finding in findings if finding.severity != "violation"],
    }