"""Eras Expert: heating cost billing domain specialist.

Eras is a German software company for Heizkostenabrechnung (heating cost billing).
Users are Hausverwaltungen and Messdienste who manage properties, meters, and billings.
"""

import asyncio
import logging

from .expert_base import ExpertNode
from ..db import run_db_query

log = logging.getLogger("runtime")


class ErasExpertNode(ExpertNode):
    name = "eras_expert"
    default_database = "eras2_production"

    DOMAIN_SYSTEM = """You are the Eras domain expert — specialist for heating cost billing (Heizkostenabrechnung).

BUSINESS CONTEXT:
Eras is a German software company. The software manages Heizkostenabrechnung according to German law (HeizKV).
The USER of this software is a Hausverwaltung (property management) or Messdienst (metering service).
They use Eras to manage their customers' properties, meters, consumption readings, and billings.

DOMAIN MODEL (how the data relates):
- Kunden (customers) = the Hausverwaltungen or property managers that the Eras user serves
  Each Kunde has a Kundennummer and contact data (Name, Adresse, etc.)

- Objekte (properties/buildings/Liegenschaften) = physical buildings managed by a Kunde
  A Kunde can have many Objekte. Each Objekt has an address and is linked to a Kunde.

- Nutzeinheiten (usage units/apartments) = individual units within an Objekt
  An Objekt contains multiple Nutzeinheiten (e.g., Wohnung 1, Wohnung 2).
  Each Nutzeinheit has Nutzer (tenants/occupants).

- Geraete (devices/meters) = measurement devices installed in Nutzeinheiten
  Heizkostenverteiler, Waermezaehler, Wasserzaehler, etc.
  Each Geraet is linked to a Nutzeinheit and has a Geraetetyp.

- Geraeteverbraeuche (consumption readings) = measured values from Geraete
  Ablesewerte collected by Monteure or remote reading systems.

- Abrechnungen (billings) = Heizkostenabrechnungen generated per Objekt/period
  The core output: distributes heating costs to Nutzeinheiten based on consumption.

- Auftraege (work orders) = tasks for Monteure (technicians)
  Device installation, reading collection, maintenance.

HIERARCHY (via JOINs):
  Kunde ←→ objektkunde ←→ Objekt (many-to-many via junction table!)
  Objekt → Nutzeinheiten → Geraete → Verbraeuche
  Nutzeinheit → Nutzer
  Kunde → Abrechnungen
  Kunde → Auftraege

CRITICAL: kunden and objekte are linked through the objektkunde junction table, NOT directly.

IMPORTANT NOTES:
- All table/column names are German, lowercase
- Foreign keys often use patterns like KundenID, ObjektID, NutzeinheitID
- The database is eras2_production
- Always DESCRIBE tables before writing JOINs to verify actual column names
- Common user questions: customer overview, device counts, billing status, Objekt details"""

    SCHEMA = """Known tables (eras2_production):
- kunden — customers (Hausverwaltungen)
- objekte — properties/buildings (Liegenschaften)
- nutzeinheit — apartments/units within Objekte
- nutzer — tenants/occupants of Nutzeinheiten
- geraete — measurement devices (Heizkostenverteiler, etc.)
- geraeteverbraeuche — consumption readings
- abrechnungen — heating cost billings
- auftraege — work orders for Monteure
- auftragspositionen — line items within Auftraege
- geraetetypen — device type catalog
- geraetekatalog — device model catalog
- heizbetriebskosten — heating operation costs
- nebenkosten — additional costs (Nebenkosten)

KNOWN SCHEMA (verified — ONLY use these column names without DESCRIBE):
All tables use ID (int, auto_increment) as primary key.

- kunden: PK=ID. Known columns: Name1, Name2, Name3, Kundennummer
- objekte: PK=ID. Known columns: Objektnummer
- objektkunde: JUNCTION TABLE for kunden↔objekte (many-to-many!)
  PK=ID, FK: KundeID→kunden.ID, ObjektID→objekte.ID
- nutzeinheit: PK=ID, FK: ObjektID→objekte.ID
- geraete: PK=ID, FK: NutzeinheitID→nutzeinheit.ID
- geraeteverbraeuche: linked to geraete
- nutzer: linked to nutzeinheit (DESCRIBE to find FK column name)

For ANY column not listed above, you MUST DESCRIBE the table first.

JOIN PATTERNS (use these exactly):
- Kunde → Objekte: JOIN objektkunde ok ON ok.KundeID = k.ID JOIN objekte o ON o.ID = ok.ObjektID
- Objekt → Nutzeinheiten: JOIN nutzeinheit n ON n.ObjektID = o.ID
- Nutzeinheit → Geraete: JOIN geraete g ON g.NutzeinheitID = n.ID

IMPORTANT: For tables not listed above, always DESCRIBE first.
The junction table objektkunde is REQUIRED to link kunden and objekte.

Example for "how many Objekte per Kunde":
[
  {{"tool": "query_db", "args": {{"query": "SELECT k.ID, k.Name1, COUNT(DISTINCT o.ID) as AnzahlObjekte FROM kunden k JOIN objektkunde ok ON ok.KundeID = k.ID JOIN objekte o ON o.ID = ok.ObjektID GROUP BY k.ID, k.Name1 ORDER BY AnzahlObjekte DESC LIMIT 20", "database": "eras2_production"}}}}
]"""

    def __init__(self, send_hud, process_manager=None):
        super().__init__(send_hud, process_manager)
        self._schema_cache: dict[str, str] = {}

    async def execute(self, job: str, language: str = "de"):
        """Execute with schema auto-discovery. Caches DESCRIBE results."""
        if self._schema_cache:
            schema_ctx = "Known column names from previous DESCRIBE:\n"
            for table, desc in self._schema_cache.items():
                lines = desc.strip().split("\n")[:8]
                schema_ctx += f"\n{table}:\n" + "\n".join(lines) + "\n"
            job = job + "\n\n" + schema_ctx

        result = await super().execute(job, language)

        # Cache DESCRIBE results
        if result.tool_output and "Field\t" in result.tool_output:
            for table in ["kunden", "objekte", "nutzeinheit", "nutzer", "geraete",
                          "geraeteverbraeuche", "abrechnungen", "auftraege"]:
                if table in job.lower() or table in result.tool_output.lower():
                    self._schema_cache[table] = result.tool_output
                    log.info(f"[eras] cached schema for {table}")
                    break

        return result