"""
app/tenant/inventory/routes.py
Inventory management: list, create, edit, adjust stock, reorder alerts.
Phase 4: automatic deduction on POS sale handled by pos/routes.py.
"""
import logging
from flask import Blueprint, render_template, redirect, url_for, flash, request, g
from flask_login import login_required
from app.extensions import db
from app.models.salon import Inventory, InventoryLog
from app.decorators import require_role, demo_readonly, tenant_feature_required
from app.tenant.utils import log_tenant_action

logger = logging.getLogger(__name__)
inventory_bp = Blueprint("inventory", __name__, url_prefix="/inventory")


@inventory_bp.route("/")
@login_required
@require_role("tenant_admin", "tenant_manager")
@tenant_feature_required("inventory")
def index():
    items = Inventory.query.filter_by(
        tenant_id=g.tenant.id, location_id=g.location.id
    ).order_by(Inventory.category, Inventory.name).all()
    low_stock = [i for i in items if i.qty_on_hand <= i.reorder_level]
    return render_template("tenant/inventory/index.html",
                           items=items, low_stock=low_stock)


@inventory_bp.route("/new", methods=["GET", "POST"])
@login_required
@require_role("tenant_admin", "tenant_manager")
@demo_readonly
@tenant_feature_required("inventory")
def create():
    if request.method == "POST":
        name = request.form.get("name", "").strip()
        if not name:
            return render_template("tenant/inventory/form.html",
                                   mode="create", error="Name is required.")
        try:
            qty = int(request.form.get("qty_on_hand", 0))
            reorder = int(request.form.get("reorder_level", 5))
        except ValueError:
            return render_template("tenant/inventory/form.html",
                                   mode="create", error="Invalid quantity or reorder level.")

        item = Inventory(
            tenant_id=g.tenant.id,
            location_id=g.location.id,
            name=name,
            sku=request.form.get("sku", "").strip() or None,
            category=request.form.get("category", "").strip() or None,
            qty_on_hand=qty,
            reorder_level=reorder,
            cost_price=_parse_decimal(request.form.get("cost_price", "")),
            sale_price=_parse_decimal(request.form.get("sale_price", "")),
        )
        db.session.add(item)
        db.session.flush()

        if qty > 0:
            db.session.add(InventoryLog(
                tenant_id=g.tenant.id, location_id=g.location.id,
                inventory_id=item.id, delta=qty, reason="Initial stock",
            ))

        log_tenant_action("inventory.create", "inventory", item.id, {"name": name})
        db.session.commit()
        flash(f"Item \'{name}\' added to inventory.", "success")
        return redirect(url_for("inventory.index"))

    return render_template("tenant/inventory/form.html", mode="create")


@inventory_bp.route("/<int:item_id>/edit", methods=["GET", "POST"])
@login_required
@require_role("tenant_admin", "tenant_manager")
@demo_readonly
@tenant_feature_required("inventory")
def edit(item_id):
    item = Inventory.query.filter_by(
        id=item_id, tenant_id=g.tenant.id, location_id=g.location.id
    ).first_or_404()

    if request.method == "POST":
        name = request.form.get("name", "").strip()
        if not name:
            return render_template("tenant/inventory/form.html",
                                   mode="edit", item=item, error="Name is required.")
        try:
            reorder = int(request.form.get("reorder_level", item.reorder_level))
        except ValueError:
            return render_template("tenant/inventory/form.html",
                                   mode="edit", item=item,
                                   error="Invalid reorder level.")

        item.name = name
        item.sku = request.form.get("sku", "").strip() or None
        item.category = request.form.get("category", "").strip() or None
        item.reorder_level = reorder
        item.cost_price = _parse_decimal(request.form.get("cost_price", ""))
        item.sale_price = _parse_decimal(request.form.get("sale_price", ""))

        log_tenant_action("inventory.edit", "inventory", item.id, {"name": name})
        db.session.commit()
        flash(f"\'{name}\' updated.", "success")
        return redirect(url_for("inventory.index"))

    return render_template("tenant/inventory/form.html", mode="edit", item=item)


@inventory_bp.route("/<int:item_id>/adjust", methods=["GET", "POST"])
@login_required
@require_role("tenant_admin", "tenant_manager")
@demo_readonly
@tenant_feature_required("inventory")
def adjust(item_id):
    item = Inventory.query.filter_by(
        id=item_id, tenant_id=g.tenant.id, location_id=g.location.id
    ).first_or_404()

    if request.method == "POST":
        try:
            delta = int(request.form.get("delta", 0))
        except ValueError:
            return render_template("tenant/inventory/adjust.html",
                                   item=item, error="Invalid adjustment quantity.")

        reason = request.form.get("reason", "").strip() or "Manual adjustment"
        new_qty = item.qty_on_hand + delta
        if new_qty < 0:
            return render_template("tenant/inventory/adjust.html",
                                   item=item,
                                   error=f"Adjustment would result in negative stock ({new_qty}).")

        item.qty_on_hand = new_qty
        db.session.add(InventoryLog(
            tenant_id=g.tenant.id, location_id=g.location.id,
            inventory_id=item.id, delta=delta, reason=reason,
        ))
        log_tenant_action("inventory.adjust", "inventory", item.id,
                          {"delta": delta, "new_qty": new_qty, "reason": reason})
        db.session.commit()
        logger.info("Inventory adjusted: item=%s delta=%s new_qty=%s",
                    item.id, delta, new_qty)
        flash(f"Stock adjusted: {item.name} now has {new_qty} units.", "success")
        return redirect(url_for("inventory.index"))

    return render_template("tenant/inventory/adjust.html", item=item)


@inventory_bp.route("/<int:item_id>/log")
@login_required
@require_role("tenant_admin", "tenant_manager")
@tenant_feature_required("inventory")
def log(item_id):
    item = Inventory.query.filter_by(
        id=item_id, tenant_id=g.tenant.id, location_id=g.location.id
    ).first_or_404()
    entries = InventoryLog.query.filter_by(
        inventory_id=item_id, tenant_id=g.tenant.id
    ).order_by(InventoryLog.created_at.desc()).limit(100).all()
    return render_template("tenant/inventory/log.html", item=item, entries=entries)


def _parse_decimal(value):
    if not value or not str(value).strip():
        return None
    try:
        return float(value)
    except ValueError:
        return None