chatbot/erp-bridge/main.py

"""
Homelegance ERP Bridge — FastAPI service
Calls chatbot_api.* stored functions in the ERP PostgreSQL database.
Listens on 127.0.0.1:8080 (internal only, never exposed to the internet).

Permission model (passed by Node.js via request headers):
  X-User-Role     : "admin" | "agent" | "user"
  X-Customer-CID  : ERP ContactID (required when role == "user")

  admin / agent  → calls *_staff function variants — sees all customers
  user (dealer)  → calls *_dealer function variants — CID enforced at DB level

Column selection is handled entirely by the chatbot_api.* functions in PostgreSQL.
The dealer variants have p_customer_cid as a mandatory parameter with no default,
making it physically impossible to return another customer's data even if this
application code is compromised.
"""

from __future__ import annotations

import json
import logging
import os
from contextlib import asynccontextmanager
from dataclasses import dataclass
from typing import Any

import asyncpg
from dotenv import load_dotenv
from fastapi import Depends, FastAPI, Header, HTTPException, Path
from pydantic import BaseModel, Field

# ──────────────────────────────────────────────────────────────────────────────
# Config
# ──────────────────────────────────────────────────────────────────────────────
load_dotenv()

ERP_DATABASE_URL: str = os.environ["ERP_DATABASE_URL"]
ERP_API_KEY: str = os.environ["ERP_API_KEY"]
PORT: int = int(os.getenv("PORT", "8080"))

logging.basicConfig(level=logging.INFO, format="%(levelname)s  %(message)s")
log = logging.getLogger(__name__)

# ──────────────────────────────────────────────────────────────────────────────
# DB Pool (lifespan)
# ──────────────────────────────────────────────────────────────────────────────
DB_POOL: asyncpg.Pool | None = None


@asynccontextmanager
async def lifespan(app: FastAPI):
    global DB_POOL
    log.info("Connecting to ERP database …")
    DB_POOL = await asyncpg.create_pool(
        ERP_DATABASE_URL,
        min_size=2,
        max_size=10,
        command_timeout=30,
        statement_cache_size=0,  # required for pgBouncer transaction mode
    )
    log.info("ERP database pool ready.")
    yield
    if DB_POOL:
        await DB_POOL.close()
    log.info("ERP database pool closed.")


app = FastAPI(
    title="Homelegance ERP Bridge",
    version="3.0.0",
    docs_url=None,   # disable Swagger UI in production
    redoc_url=None,
    lifespan=lifespan,
)

# ──────────────────────────────────────────────────────────────────────────────
# Auth & permission dependencies
# ──────────────────────────────────────────────────────────────────────────────

def verify_api_key(x_api_key: str = Header(..., alias="X-API-Key")) -> None:
    if x_api_key != ERP_API_KEY:
        raise HTTPException(status_code=401, detail="Invalid API key")


@dataclass
class UserCtx:
    role: str          # "admin" | "agent" | "user"
    customer_cid: str | None  # ERP ContactID; required when role == "user"

    @property
    def is_staff(self) -> bool:
        return self.role in ("admin", "agent")

    @property
    def is_dealer(self) -> bool:
        return self.role == "user"


def get_user_ctx(
    x_user_role: str = Header("admin", alias="X-User-Role"),
    x_customer_cid: str | None = Header(None, alias="X-Customer-CID"),
) -> UserCtx:
    role = x_user_role.lower().strip()
    if role not in ("admin", "agent", "user"):
        role = "admin"  # safe default for unknown values
    if role == "user" and not x_customer_cid:
        raise HTTPException(
            status_code=403,
            detail="X-Customer-CID header required for dealer (user) role",
        )
    return UserCtx(role=role, customer_cid=x_customer_cid)


# ──────────────────────────────────────────────────────────────────────────────
# DB call helpers
# ──────────────────────────────────────────────────────────────────────────────

async def call_list(sql: str, *args: Any) -> list[dict]:
    """Call a chatbot_api function that returns a JSON array."""
    assert DB_POOL is not None
    row = await DB_POOL.fetchrow(sql, *args)
    if row is None or row[0] is None:
        return []
    data = json.loads(row[0]) if isinstance(row[0], str) else row[0]
    return data if isinstance(data, list) else []


async def call_single(sql: str, *args: Any) -> dict | None:
    """Call a chatbot_api function that returns a single JSON object (or NULL)."""
    assert DB_POOL is not None
    row = await DB_POOL.fetchrow(sql, *args)
    if row is None or row[0] is None:
        return None
    data = json.loads(row[0]) if isinstance(row[0], str) else row[0]
    return data if isinstance(data, dict) else None


# ──────────────────────────────────────────────────────────────────────────────
# Request models
# ──────────────────────────────────────────────────────────────────────────────

class CatalogRequest(BaseModel):
    model: str | None = Field(None, description="Partial model number (ILIKE)")
    description: str | None = Field(None, description="Description keyword")
    # manufacturer and category are accepted for API compatibility but are
    # combined into the keyword search — chatbot_api.catalog_search searches
    # model + description fields only
    manufacturer: str | None = Field(None, description="Manufacturer (combined into keyword)")
    category: str | None = Field(None, description="Category (combined into keyword)")
    status: str | None = Field(None, description="Item status (not filtered at DB level)")
    limit: int = Field(20, ge=1, le=200)


class ContactsRequest(BaseModel):
    contact_id: str | None = Field(None, description="ContactID (exact)")
    company: str | None = Field(None, description="Company name (partial)")
    name: str | None = Field(None, description="Contact person name (not used, for API compat)")
    limit: int = Field(20, ge=1, le=200)


class OrdersListRequest(BaseModel):
    so_id: str | None = Field(None, description="Sales Order ID")
    customer_name: str | None = Field(None, description="Customer name (partial, staff only)")
    customer_cid: str | None = Field(None, description="Customer CID — overridden for dealer role")
    po_id: str | None = Field(None, description="PO number")
    status: str | None = Field(None, description="Order status")
    limit: int = Field(20, ge=1, le=200)


class StockRequest(BaseModel):
    model: str | None = Field(None, description="Model number (partial)")
    warehouse_cid: str | None = Field(None, description="Warehouse code")
    limit: int = Field(50, ge=1, le=500)


# ──────────────────────────────────────────────────────────────────────────────
# Endpoints
# ──────────────────────────────────────────────────────────────────────────────

@app.get("/health")
async def health() -> dict:
    """Liveness probe — no auth required."""
    return {"status": "ok", "service": "erp-bridge", "version": "3.0.0"}


@app.post("/catalog", dependencies=[Depends(verify_api_key)])
async def catalog_search(
    req: CatalogRequest,
    ctx: UserCtx = Depends(get_user_ctx),
) -> list[dict[str, Any]]:
    """Search the product catalog. Catalog is not customer-scoped."""
    # Combine description, manufacturer, category into a single keyword search
    keyword_parts = [p for p in [req.description, req.manufacturer, req.category] if p]
    keyword = " ".join(keyword_parts) or None

    return await call_list(
        "SELECT chatbot_api.catalog_search($1, $2, $3)",
        keyword, req.model, req.limit,
    )


@app.post("/contacts", dependencies=[Depends(verify_api_key)])
async def contacts_search(
    req: ContactsRequest,
    ctx: UserCtx = Depends(get_user_ctx),
) -> list[dict[str, Any]]:
    """
    Search customers/contacts.
    Dealer role is scoped to their own record at the DB level.
    """
    if ctx.is_dealer:
        # contact_get_dealer returns a single object; wrap in list for consistent response
        record = await call_single(
            "SELECT chatbot_api.contact_get_dealer($1)",
            ctx.customer_cid,
        )
        return [record] if record else []
    else:
        return await call_list(
            "SELECT chatbot_api.contact_get_staff($1, $2, $3)",
            req.company, req.contact_id, req.limit,
        )


@app.post("/orders", dependencies=[Depends(verify_api_key)])
async def orders_list(
    req: OrdersListRequest,
    ctx: UserCtx = Depends(get_user_ctx),
) -> list[dict[str, Any]]:
    """
    List sales orders.
    Dealer variant enforces CustomerCID at the DB level — cannot be bypassed.
    """
    if ctx.is_dealer:
        return await call_list(
            "SELECT chatbot_api.orders_list_dealer($1, $2, $3, $4, $5)",
            ctx.customer_cid, req.so_id, req.po_id, req.status, req.limit,
        )
    else:
        return await call_list(
            "SELECT chatbot_api.orders_list_staff($1, $2, $3, $4, $5, $6)",
            req.so_id, req.po_id, req.customer_cid, req.customer_name, req.status, req.limit,
        )


@app.get("/orders/{so_id}", dependencies=[Depends(verify_api_key)])
async def order_get(
    so_id: str = Path(..., description="Sales Order ID"),
    ctx: UserCtx = Depends(get_user_ctx),
) -> dict[str, Any]:
    """
    Get a single sales order with line items and notes.
    Dealer variant validates CID match at the DB level and returns NULL on mismatch
    (treated as 404 — prevents order-ID enumeration).
    """
    if ctx.is_dealer:
        result = await call_single(
            "SELECT chatbot_api.order_get_dealer($1, $2)",
            so_id, ctx.customer_cid,
        )
    else:
        result = await call_single(
            "SELECT chatbot_api.order_get_staff($1)",
            so_id,
        )

    if result is None:
        raise HTTPException(status_code=404, detail=f"Sales order not found: {so_id}")

    return result


@app.post("/stock", dependencies=[Depends(verify_api_key)])
async def stock_search(
    req: StockRequest,
    ctx: UserCtx = Depends(get_user_ctx),
) -> list[dict[str, Any]]:
    """
    Search available stock.
    Dealer variant returns availability info only (no pallet/hold/logistics detail).
    """
    if not req.model:
        return []

    if ctx.is_dealer:
        return await call_list(
            "SELECT chatbot_api.stock_search_dealer($1, $2, $3)",
            req.model, req.warehouse_cid, req.limit,
        )
    else:
        return await call_list(
            "SELECT chatbot_api.stock_search_staff($1, $2, $3)",
            req.model, req.warehouse_cid, req.limit,
        )


# ──────────────────────────────────────────────────────────────────────────────
# Dev runner (production uses uvicorn via systemd)
# ──────────────────────────────────────────────────────────────────────────────
if __name__ == "__main__":
    import uvicorn
    uvicorn.run("main:app", host="127.0.0.1", port=PORT, reload=False)