from __future__ import annotations

import json
import re
from decimal import Decimal, InvalidOperation
from typing import Any

from pydantic import ValidationError
from sqlalchemy.orm import Session

from app.services.document_intelligence_rules import DEFAULT_RULE, DOCUMENT_RULES, DOCUMENT_TYPE_RULE_MAP, SUPPORTED_DOCUMENT_TYPES
from app.services.document_intelligence_types import (
    DocumentField,
    DocumentInsight,
    LlmDocumentClassification,
    RuleMatch,
)


AMOUNT_PATTERNS = (
    re.compile(
        r"(?:价税合计|合计金额|费用合计|总费用|费用总计|订单(?:总)?金额|支付(?:金额)?|实付(?:金额)?|实收(?:金额)?|总(?:额|计|价)|票价|金额|车费|消费金额|房费|住宿费)"
        r"[：:\s￥¥人民币为是]*([0-9]+(?:[.,][0-9]{1,2})?)"
    ),
    re.compile(r"[￥¥]\s*([0-9]+(?:[.,][0-9]{1,2})?)"),
    re.compile(r"([0-9]+(?:[.,][0-9]{1,2})?)\s*元"),
)
DATE_PATTERN = re.compile(r"((?:20\d{2}|19\d{2})[-/年.](?:1[0-2]|0?[1-9])[-/月.](?:3[01]|[12]\d|0?[1-9])日?)")
TIME_PATTERN = re.compile(r"(?<!\d)([01]?\d|2[0-3])[:：]([0-5]\d)(?!\d)")
INVOICE_NUMBER_PATTERN = re.compile(r"(?:发票号码|票号|单号|订单号)[：:\s]*([A-Za-z0-9-]{6,24})")
INVOICE_CODE_PATTERN = re.compile(r"(?:发票代码)[：:\s]*([A-Za-z0-9-]{6,24})")
TRIP_NO_PATTERN = re.compile(r"(?:车次|航班(?:号)?)[：:\s]*([A-Za-z0-9]{2,12})")
ROUTE_PATTERN = re.compile(r"([\u4e00-\u9fa5]{2,12})\s*(?:至|→|->|-)\s*([\u4e00-\u9fa5]{2,12})")
MERCHANT_PATTERNS = (
    re.compile(r"(?:销售方(?:名称)?|商户(?:名称)?|开票方(?:名称)?|收款方(?:名称)?)[：:\s]*([A-Za-z0-9\u4e00-\u9fa5（）()·&\\-]{2,40})"),
    re.compile(r"([A-Za-z0-9\u4e00-\u9fa5（）()·&\\-]{2,40}(?:酒店|宾馆|饭店|酒楼|餐厅|航空|铁路|滴滴出行|停车场|服务区))"),
)
DATE_FIELD_KEYS = {
    "date",
    "time",
    "issued_at",
    "invoice_date",
    "issue_date",
    "travel_date",
    "trip_date",
    "journey_date",
    "departure_date",
    "departure_time",
    "depart_date",
    "depart_time",
    "boarding_date",
    "boarding_time",
    "train_date",
    "train_time",
    "train_departure_time",
    "scheduled_departure_time",
    "flight_date",
    "flight_time",
    "ride_date",
    "ride_time",
    "pickup_time",
    "start_time",
}
TRIP_DATE_LABEL_BY_DOCUMENT_TYPE = {
    "train_ticket": "列车出发时间",
    "flight_itinerary": "起飞日期",
    "taxi_receipt": "乘车时间",
    "transport_receipt": "乘车时间",
    "parking_toll_receipt": "通行日期",
}
TRIP_DATE_FIELD_LABEL_TOKENS = (
    "日期",
    "时间",
    "开票日期",
    "发生时间",
    "行程日期",
    "出发日期",
    "出发时间",
    "列车出发时间",
    "发车日期",
    "发车时间",
    "开车时间",
    "乘车日期",
    "乘车时间",
    "起飞日期",
    "航班日期",
    "上车时间",
    "用车时间",
)


class DocumentIntelligenceService:
    def __init__(self, db: Session | None = None) -> None:
        self.db = db

    def build_document_insight(
        self,
        *,
        filename: str = "",
        summary: str = "",
        text: str = "",
        preview_data_url: str = "",
    ) -> DocumentInsight:
        raw_text = " ".join(
            [str(filename or "").strip(), str(summary or "").strip(), str(text or "").strip()]
        ).strip()
        compact = re.sub(r"\s+", "", raw_text).lower()
        rule_match = _match_document_rule(compact)
        base_rule = rule_match.rule or DEFAULT_RULE
        fields = _apply_document_type_field_labels(
            tuple(_extract_document_fields(raw_text, base_rule.document_type)),
            base_rule.document_type,
        )
        rule_insight = DocumentInsight(
            document_type=base_rule.document_type,
            document_type_label=base_rule.document_type_label,
            scene_code=base_rule.scene_code,
            scene_label=base_rule.scene_label,
            expense_type=base_rule.expense_type,
            fields=fields,
            classification_source="rule",
            classification_confidence=rule_match.confidence,
            evidence=rule_match.evidence,
        )

        llm_result = self._classify_with_model(
            filename=str(filename or "").strip(),
            summary=str(summary or "").strip(),
            text=str(text or "").strip(),
            preview_data_url=str(preview_data_url or "").strip(),
            rule_insight=rule_insight,
            fields=fields,
        )
        if llm_result is None:
            return rule_insight
        return self._merge_rule_and_model(
            rule_insight=rule_insight,
            llm_result=llm_result,
            fields=fields,
            has_preview=bool(preview_data_url),
        )

    def _classify_with_model(
        self,
        *,
        filename: str,
        summary: str,
        text: str,
        preview_data_url: str,
        rule_insight: DocumentInsight,
        fields: tuple[DocumentField, ...],
    ) -> tuple[str, LlmDocumentClassification] | None:
        return None

    @staticmethod
    def _parse_llm_payload(response_text: str | None) -> LlmDocumentClassification | None:
        payload_json = _extract_json_payload(response_text)
        if payload_json is None:
            return None

        try:
            parsed = LlmDocumentClassification.model_validate(payload_json)
        except ValidationError:
            return None

        normalized_type = str(parsed.document_type or "other").strip().lower() or "other"
        if normalized_type not in SUPPORTED_DOCUMENT_TYPES:
            normalized_type = "other"

        base_rule = DOCUMENT_TYPE_RULE_MAP.get(normalized_type, DEFAULT_RULE)
        evidence = [
            str(item or "").strip()
            for item in parsed.evidence
            if str(item or "").strip()
        ][:4]
        normalized_fields = _apply_document_type_field_labels(
            tuple(_normalize_llm_document_fields(parsed.fields)),
            normalized_type,
        )

        return LlmDocumentClassification(
            document_type=normalized_type,
            scene_code=str(parsed.scene_code or base_rule.scene_code).strip() or base_rule.scene_code,
            scene_label=str(parsed.scene_label or base_rule.scene_label).strip() or base_rule.scene_label,
            expense_type=str(parsed.expense_type or base_rule.expense_type).strip() or base_rule.expense_type,
            confidence=float(parsed.confidence),
            evidence=evidence,
            fields=normalized_fields,
        )

    @staticmethod
    def _merge_rule_and_model(
        *,
        rule_insight: DocumentInsight,
        llm_result: tuple[str, LlmDocumentClassification],
        fields: tuple[DocumentField, ...],
        has_preview: bool,
    ) -> DocumentInsight:
        source, parsed = llm_result
        warnings = list(rule_insight.warnings)
        merged_fields = rule_insight.fields
        if parsed.fields and (has_preview or parsed.confidence >= 0.55):
            merged_fields = _merge_document_fields(rule_insight.fields, tuple(parsed.fields))
            if merged_fields != rule_insight.fields:
                warnings.append("票据关键信息已结合大模型复核结果修正，建议人工再核对原图。")

        if parsed.confidence < 0.55:
            if merged_fields == rule_insight.fields:
                return rule_insight
            return DocumentInsight(
                document_type=rule_insight.document_type,
                document_type_label=rule_insight.document_type_label,
                scene_code=rule_insight.scene_code,
                scene_label=rule_insight.scene_label,
                expense_type=rule_insight.expense_type,
                fields=_apply_document_type_field_labels(
                    merged_fields,
                    rule_insight.document_type,
                ),
                classification_source=rule_insight.classification_source,
                classification_confidence=rule_insight.classification_confidence,
                evidence=rule_insight.evidence,
                warnings=tuple(warnings),
            )

        should_override = False
        if parsed.document_type == rule_insight.document_type:
            should_override = True
        elif rule_insight.document_type == "other" and parsed.document_type != "other":
            should_override = True
        elif parsed.document_type != "other":
            threshold = 0.60 if has_preview else max(0.76, rule_insight.classification_confidence + 0.12)
            should_override = parsed.confidence >= threshold

        if not should_override:
            if merged_fields == rule_insight.fields:
                return rule_insight
            return DocumentInsight(
                document_type=rule_insight.document_type,
                document_type_label=rule_insight.document_type_label,
                scene_code=rule_insight.scene_code,
                scene_label=rule_insight.scene_label,
                expense_type=rule_insight.expense_type,
                fields=_apply_document_type_field_labels(
                    merged_fields,
                    rule_insight.document_type,
                ),
                classification_source=rule_insight.classification_source,
                classification_confidence=rule_insight.classification_confidence,
                evidence=rule_insight.evidence,
                warnings=tuple(warnings),
            )

        rule = DOCUMENT_TYPE_RULE_MAP.get(parsed.document_type, DEFAULT_RULE)
        if parsed.document_type != rule_insight.document_type:
            warnings.append("票据类型已结合大模型复核结果修正，建议人工再核对原图。")

        return DocumentInsight(
            document_type=rule.document_type,
            document_type_label=rule.document_type_label,
            scene_code=rule.scene_code if parsed.scene_code == "other" else parsed.scene_code,
            scene_label=rule.scene_label if parsed.scene_label == "其他票据" else parsed.scene_label,
            expense_type=rule.expense_type if parsed.expense_type == "other" else parsed.expense_type,
            fields=_apply_document_type_field_labels(merged_fields, rule.document_type),
            classification_source=source,
            classification_confidence=max(parsed.confidence, rule_insight.classification_confidence),
            evidence=tuple(parsed.evidence or rule_insight.evidence),
            warnings=tuple(warnings),
        )


def build_document_insight(
    *,
    filename: str = "",
    summary: str = "",
    text: str = "",
    preview_data_url: str = "",
) -> DocumentInsight:
    return DocumentIntelligenceService().build_document_insight(
        filename=filename,
        summary=summary,
        text=text,
        preview_data_url=preview_data_url,
    )


def _match_document_rule(compact_text: str) -> RuleMatch:
    best_rule = DEFAULT_RULE
    best_evidence: tuple[str, ...] = ()
    best_score = 0.0

    for rule in DOCUMENT_RULES:
        matched = tuple(keyword for keyword in rule.keywords if keyword.lower() in compact_text)
        if not matched:
            continue
        score = float(rule.score_bias) + len(matched) * 0.92 + sum(min(len(keyword), 6) * 0.08 for keyword in matched)
        if score > best_score:
            best_rule = rule
            best_evidence = matched
            best_score = score

    if best_score <= 0:
        return RuleMatch(rule=None, confidence=0.0, evidence=(), score=0.0)

    confidence = min(0.94, 0.30 + min(best_score, 4.8) * 0.12)
    return RuleMatch(
        rule=best_rule,
        confidence=round(confidence, 2),
        evidence=best_evidence[:4],
        score=best_score,
    )


def _extract_json_payload(response_text: str | None) -> dict[str, Any] | None:
    if not response_text:
        return None

    cleaned = re.sub(r"<think>.*?</think>", "", response_text, flags=re.DOTALL | re.IGNORECASE).strip()
    if not cleaned:
        return None

    fenced_match = re.search(r"```(?:json)?\s*(\{.*\})\s*```", cleaned, flags=re.DOTALL)
    candidates = [fenced_match.group(1)] if fenced_match else []
    candidates.append(cleaned)

    start = cleaned.find("{")
    end = cleaned.rfind("}")
    if start != -1 and end != -1 and end > start:
        candidates.append(cleaned[start : end + 1])

    for candidate in candidates:
        try:
            parsed = json.loads(candidate)
        except json.JSONDecodeError:
            continue
        if isinstance(parsed, dict):
            return parsed
    return None


def _normalize_llm_document_fields(raw_fields: list[DocumentField] | list[dict[str, Any]]) -> list[DocumentField]:
    normalized: list[DocumentField] = []
    seen_keys: set[str] = set()

    for field in raw_fields:
        raw_key = str(getattr(field, "key", "") if isinstance(field, DocumentField) else field.get("key") or "").strip()
        raw_label = str(getattr(field, "label", "") if isinstance(field, DocumentField) else field.get("label") or "").strip()
        raw_value = str(getattr(field, "value", "") if isinstance(field, DocumentField) else field.get("value") or "").strip()
        key = _normalize_llm_document_field_key(raw_key, raw_label)
        if not key or key in seen_keys:
            continue
        value = _normalize_llm_document_field_value(key, raw_value)
        if not value:
            continue
        seen_keys.add(key)
        normalized.append(
            DocumentField(
                key=key,
                label=_llm_document_field_label(key),
                value=value,
            )
        )

    return normalized


def _normalize_llm_document_field_key(key: str, label: str) -> str:
    compact_key = str(key or "").strip().lower()
    compact_label = str(label or "").replace(" ", "").lower()
    if compact_key in {"amount", "total_amount", "payment_amount", "paid_amount"} or any(
        token in compact_label for token in ("金额", "价税合计", "合计", "总额", "总计", "票价", "支付金额", "实付金额", "实收金额")
    ):
        return "amount"
    if compact_key in {
        "travel_date",
        "trip_date",
        "journey_date",
        "departure_date",
        "departure_time",
        "depart_date",
        "depart_time",
        "boarding_date",
        "boarding_time",
        "train_date",
        "train_time",
        "train_departure_time",
        "scheduled_departure_time",
        "flight_date",
        "flight_time",
        "ride_date",
        "ride_time",
        "pickup_time",
        "start_time",
    } or any(
        token in compact_label
        for token in (
            "行程日期",
            "出发日期",
            "出发时间",
            "列车出发时间",
            "发车日期",
            "发车时间",
            "开车时间",
            "乘车日期",
            "乘车时间",
            "起飞日期",
            "航班日期",
            "上车时间",
            "用车时间",
        )
    ):
        return "trip_date"
    if compact_key in {"issued_at", "issue_date", "invoice_date"} or "开票日期" in compact_label:
        return "invoice_date"
    if compact_key in {"date", "time"} or any(
        token in compact_label for token in ("日期", "时间", "发生时间")
    ):
        return "date"
    if compact_key in {"merchant_name", "merchant", "seller_name", "vendor_name"} or any(
        token in compact_label for token in ("商户", "酒店", "销售方", "开票方", "收款方")
    ):
        return "merchant_name"
    if compact_key in {"invoice_number", "ticket_number", "order_no", "order_number"} or any(
        token in compact_label for token in ("票据号码", "发票号码", "票号", "单号", "订单号")
    ):
        return "invoice_number"
    if compact_key in {"invoice_code"} or "发票代码" in compact_label:
        return "invoice_code"
    if compact_key in {"trip_no", "flight_no", "train_no"} or any(
        token in compact_label for token in ("车次", "航班")
    ):
        return "trip_no"
    if compact_key in {"route", "trip_route"} or any(token in compact_label for token in ("行程", "路线")):
        return "route"
    return ""


def _normalize_llm_document_field_value(key: str, value: str) -> str:
    raw_value = str(value or "").strip()
    if not raw_value:
        return ""
    if key == "amount":
        amount = _extract_amount(raw_value)
        if amount:
            return amount
        cleaned = raw_value.replace("￥", "").replace("¥", "").replace("元", "").replace(",", ".").strip()
        try:
            candidate = Decimal(cleaned)
        except InvalidOperation:
            return ""
        if candidate <= Decimal("0.00"):
            return ""
        text_value = format(candidate.quantize(Decimal("0.01")), "f").rstrip("0").rstrip(".")
        return f"{text_value}元"
    if key in {"date", "time", "invoice_date", "trip_date"}:
        return _extract_date(raw_value) or _clean_field_value(raw_value)
    if key == "route":
        return _extract_route(raw_value) or _clean_field_value(
            raw_value.replace("→", "-").replace("至", "-").replace("->", "-")
        )
    return _clean_field_value(raw_value)


def _llm_document_field_label(key: str) -> str:
    return {
        "amount": "金额",
        "date": "日期",
        "invoice_date": "开票日期",
        "trip_date": "行程日期",
        "merchant_name": "商户",
        "invoice_number": "票据号码",
        "invoice_code": "发票代码",
        "trip_no": "车次/航班",
        "route": "行程",
    }.get(key, key)


def _apply_document_type_field_labels(
    fields: tuple[DocumentField, ...],
    document_type: str,
) -> tuple[DocumentField, ...]:
    date_label = TRIP_DATE_LABEL_BY_DOCUMENT_TYPE.get(
        str(document_type or "").strip().lower()
    )
    if not date_label:
        return fields

    adjusted: list[DocumentField] = []
    for field in fields:
        compact_key = str(field.key or "").strip().lower()
        compact_label = str(field.label or "").replace(" ", "")
        if compact_key in {"issued_at", "issue_date", "invoice_date"} or any(
            token in compact_label for token in ("开票日期", "发票日期")
        ):
            adjusted.append(field)
            continue
        is_date_field = compact_key in DATE_FIELD_KEYS or any(
            token in compact_label for token in TRIP_DATE_FIELD_LABEL_TOKENS
        )
        if is_date_field:
            adjusted.append(DocumentField(key=field.key, label=date_label, value=field.value))
            continue
        adjusted.append(field)
    return tuple(adjusted)


def _merge_document_fields(
    base_fields: tuple[DocumentField, ...],
    override_fields: tuple[DocumentField, ...],
) -> tuple[DocumentField, ...]:
    merged = {field.key: field for field in base_fields if field.key and field.value}
    order = [field.key for field in base_fields if field.key and field.value]
    for field in override_fields:
        if not field.key or not field.value:
            continue
        merged[field.key] = field
        if field.key not in order:
            order.append(field.key)
    return tuple(merged[key] for key in order if key in merged)


def _extract_document_fields(text: str, document_type: str = "") -> list[DocumentField]:
    fields: list[DocumentField] = []
    amount = _extract_amount(text)
    if amount:
        fields.append(DocumentField(key="amount", label="金额", value=amount))

    date_value = _extract_date(text, document_type=document_type)
    if date_value:
        fields.append(DocumentField(key="date", label="日期", value=date_value))

    merchant = _extract_merchant(text)
    if merchant:
        fields.append(DocumentField(key="merchant_name", label="商户", value=merchant))

    invoice_number = _extract_pattern(INVOICE_NUMBER_PATTERN, text)
    if invoice_number:
        fields.append(DocumentField(key="invoice_number", label="票据号码", value=invoice_number))

    invoice_code = _extract_pattern(INVOICE_CODE_PATTERN, text)
    if invoice_code:
        fields.append(DocumentField(key="invoice_code", label="发票代码", value=invoice_code))

    trip_no = _extract_pattern(TRIP_NO_PATTERN, text)
    if trip_no:
        fields.append(DocumentField(key="trip_no", label="车次/航班", value=trip_no))

    route = _extract_route(text)
    if route:
        fields.append(DocumentField(key="route", label="行程", value=route))

    return fields


def _extract_amount(text: str) -> str:
    best_value: Decimal | None = None
    for pattern in AMOUNT_PATTERNS:
        for match in pattern.finditer(text):
            raw_value = str(match.group(1) or "").replace(",", ".").strip()
            try:
                candidate = Decimal(raw_value)
            except InvalidOperation:
                continue
            if candidate <= Decimal("0.00"):
                continue
            if _is_amount_match_date_fragment(candidate, text, match.start(1), match.end(1)):
                continue
            if best_value is None or candidate > best_value:
                best_value = candidate

    if best_value is None:
        return ""
    normalized = best_value.quantize(Decimal("0.01"))
    text_value = format(normalized, "f").rstrip("0").rstrip(".")
    return f"{text_value}元"


def _is_amount_match_date_fragment(amount: Decimal, text: str, start: int, end: int) -> bool:
    if start < 0 or end < 0:
        return False
    normalized = amount.quantize(Decimal("0.01"))
    if normalized != normalized.to_integral_value() or normalized < Decimal("1900") or normalized > Decimal("2099"):
        return False

    before = str(text or "")[max(0, start - 8):start]
    after = str(text or "")[end:end + 10]
    if re.match(r"\s*(?:年|[-/.])\s*\d{1,2}", after):
        return True
    if re.search(r"\d{1,2}\s*(?:年|[-/.])\s*$", before):
        return True
    return False


def _extract_date(text: str, *, document_type: str = "") -> str:
    matches = list(DATE_PATTERN.finditer(text))
    if not matches:
        return ""

    normalized_type = str(document_type or "").strip().lower()
    if normalized_type in TRIP_DATE_LABEL_BY_DOCUMENT_TYPE:
        candidates: list[tuple[int, int, bool, str]] = []
        for index, match in enumerate(matches):
            value = _format_date_match_with_time(text, match)
            if not value:
                continue
            invoice_context = _is_invoice_date_context(text, match)
            score = _score_trip_date_context(text, match, value, invoice_context)
            candidates.append((score, index, invoice_context, value))

        non_invoice_candidates = [candidate for candidate in candidates if not candidate[2]]
        if non_invoice_candidates:
            return max(non_invoice_candidates, key=lambda candidate: (candidate[0], -candidate[1]))[3]
        if candidates:
            return ""
        return ""

    return _format_date_match_with_time(text, matches[0])


def _format_date_match_with_time(text: str, match: re.Match[str]) -> str:
    raw_value = str(match.group(1) or "").strip()
    normalized = raw_value.replace("年", "-").replace("月", "-").replace("日", "")
    normalized = normalized.replace("/", "-").replace(".", "-")
    parts = [part for part in normalized.split("-") if part]
    if len(parts) != 3:
        return raw_value
    year, month, day = parts
    date_value = f"{year.zfill(4)}-{month.zfill(2)}-{day.zfill(2)}"
    surrounding = str(text or "")[max(0, match.start() - 18): match.end() + 24]
    time_match = TIME_PATTERN.search(surrounding)
    if time_match:
        hour = str(time_match.group(1) or "").zfill(2)
        minute = str(time_match.group(2) or "").zfill(2)
        return f"{date_value} {hour}:{minute}"
    return date_value


def _is_invoice_date_context(text: str, match: re.Match[str]) -> bool:
    window = str(text or "")[max(0, match.start() - 12): match.end() + 8]
    compact = window.replace(" ", "")
    return any(token in compact for token in ("开票日期", "发票日期", "开票时间", "开票"))


def _score_trip_date_context(
    text: str,
    match: re.Match[str],
    value: str,
    invoice_context: bool,
) -> int:
    window = str(text or "")[max(0, match.start() - 32): match.end() + 32]
    compact = window.replace(" ", "")
    score = -20 if invoice_context else 0
    if ":" in value or "：" in value:
        score += 8
    if any(
        token in compact
        for token in (
            "行程日期",
            "出发日期",
            "出发时间",
            "列车出发时间",
            "发车日期",
            "发车时间",
            "开车时间",
            "乘车日期",
            "乘车时间",
            "起飞日期",
            "起飞时间",
            "航班日期",
            "上车时间",
            "用车时间",
        )
    ):
        score += 6
    if any(token in compact for token in ("车次", "检票", "二等座", "一等座", "商务座", "软卧", "硬卧")):
        score += 3
    if re.search(r"[A-Z]\d{1,4}", compact):
        score += 2
    if re.search(r"[\u4e00-\u9fa5A-Za-z0-9（）()·]{2,20}(?:至|到|→|->|—|–|-)[\u4e00-\u9fa5A-Za-z0-9（）()·]{2,20}", compact):
        score += 2
    return score


def _extract_merchant(text: str) -> str:
    for pattern in MERCHANT_PATTERNS:
        match = pattern.search(text)
        if not match:
            continue
        value = _clean_field_value(match.group(1))
        if value:
            return value
    return ""


def _extract_route(text: str) -> str:
    match = ROUTE_PATTERN.search(text)
    if not match:
        return ""
    start = _clean_field_value(match.group(1))
    end = _clean_field_value(match.group(2))
    if not start or not end or start == end:
        return ""
    return f"{start}-{end}"


def _extract_pattern(pattern: re.Pattern[str], text: str) -> str:
    match = pattern.search(text)
    if not match:
        return ""
    return _clean_field_value(match.group(1))


def _clean_field_value(value: str) -> str:
    return str(value or "").strip().strip("：:，,。.；;")