"""ERP Sync Engine: Aspel SAE, Contpaqi, SAP B1, Odoo integration stubs.

This module provides the architecture for bidirectional sync between Nexus POS
and external ERP systems. Actual implementations require:
  - Aspel SAE: ODBC connection or REST API via Aspel NOI/SAE middleware
  - Contpaqi: Contpaqi SDK or REST API via Facturama/Contpaqi middleware
  - SAP B1: Service Layer REST API
  - Odoo: XML-RPC or JSON-RPC API

Tables (erp_sync_configs, erp_sync_logs, erp_sync_queue) created in v2.6.
"""

from datetime import datetime

ERP_HANDLERS = {}


def register_erp_handler(erp_type, handler_class):
    ERP_HANDLERS[erp_type] = handler_class


def get_erp_handler(erp_type):
    return ERP_HANDLERS.get(erp_type)


# ─── ERP Sync Configuration ─────────────────────────────

def create_sync_config(conn, tenant_id, erp_type, api_endpoint, api_username,
                       api_password, database_name=None, company_code=None,
                       sync_direction='bidirectional', sync_inventory=False,
                       sync_sales=False, sync_customers=False,
                       sync_frequency_minutes=60):
    cur = conn.cursor()
    cur.execute("""
        INSERT INTO erp_sync_configs
            (tenant_id, erp_type, api_endpoint, api_username, api_password_encrypted,
             database_name, company_code, sync_direction, sync_inventory,
             sync_sales, sync_customers, sync_frequency_minutes)
        VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
        RETURNING id
    """, (tenant_id, erp_type, api_endpoint, api_username, api_password,
          database_name, company_code, sync_direction, sync_inventory,
          sync_sales, sync_customers, sync_frequency_minutes))
    config_id = cur.fetchone()[0]
    conn.commit()
    cur.close()
    return config_id


def get_sync_config(conn, tenant_id, erp_type):
    cur = conn.cursor()
    cur.execute("""
        SELECT id, tenant_id, erp_type, is_active, api_endpoint, api_username,
               database_name, company_code, sync_direction, sync_inventory,
               sync_sales, sync_customers, sync_frequency_minutes,
               last_sync_at, last_sync_error, created_at
        FROM erp_sync_configs
        WHERE tenant_id = %s AND erp_type = %s
    """, (tenant_id, erp_type))
    row = cur.fetchone()
    cur.close()
    if not row:
        return None
    return {
        'id': row[0], 'tenant_id': row[1], 'erp_type': row[2],
        'is_active': row[3], 'api_endpoint': row[4], 'api_username': row[5],
        'database_name': row[6], 'company_code': row[7],
        'sync_direction': row[8], 'sync_inventory': row[9],
        'sync_sales': row[10], 'sync_customers': row[11],
        'sync_frequency_minutes': row[12],
        'last_sync_at': str(row[13]) if row[13] else None,
        'last_sync_error': row[14], 'created_at': str(row[15]),
    }


# ─── Sync Queue ─────────────────────────────

def queue_for_sync(conn, config_id, entity_type, entity_id, action='update',
                   priority=5):
    """Add an entity to the sync queue."""
    cur = conn.cursor()
    cur.execute("""
        INSERT INTO erp_sync_queue
            (config_id, entity_type, entity_id, action, priority)
        VALUES (%s, %s, %s, %s, %s)
        ON CONFLICT DO NOTHING
        RETURNING id
    """, (config_id, entity_type, entity_id, action, priority))
    row = cur.fetchone()
    conn.commit()
    cur.close()
    return row[0] if row else None


def get_pending_queue(conn, config_id, limit=100):
    cur = conn.cursor()
    cur.execute("""
        SELECT id, entity_type, entity_id, action, priority, retry_count, created_at
        FROM erp_sync_queue
        WHERE config_id = %s AND status IN ('pending', 'failed')
        ORDER BY priority ASC, created_at ASC
        LIMIT %s
    """, (config_id, limit))
    items = []
    for r in cur.fetchall():
        items.append({
            'id': r[0], 'entity_type': r[1], 'entity_id': r[2],
            'action': r[3], 'priority': r[4], 'retry_count': r[5],
            'created_at': str(r[6]),
        })
    cur.close()
    return items


def mark_queue_item(conn, queue_id, status, error=None):
    cur = conn.cursor()
    if status == 'completed':
        cur.execute("""
            UPDATE erp_sync_queue
            SET status = %s, processed_at = NOW(), last_error = NULL
            WHERE id = %s
        """, (status, queue_id))
    elif status == 'failed':
        cur.execute("""
            UPDATE erp_sync_queue
            SET status = %s, retry_count = retry_count + 1, last_error = %s
            WHERE id = %s
        """, (status, error, queue_id))
    conn.commit()
    cur.close()


# ─── Sync Logs ─────────────────────────────

def log_sync_run(conn, config_id, sync_type, direction, status,
                 records_processed=0, records_failed=0, error_message=None,
                 details=None):
    cur = conn.cursor()
    cur.execute("""
        INSERT INTO erp_sync_logs
            (config_id, sync_type, direction, status, records_processed,
             records_failed, error_message, details)
        VALUES (%s, %s, %s, %s, %s, %s, %s, %s)
        RETURNING id
    """, (config_id, sync_type, direction, status, records_processed,
          records_failed, error_message, details))
    log_id = cur.fetchone()[0]
    conn.commit()
    cur.close()
    return log_id


def complete_sync_run(conn, log_id, status, records_processed, records_failed,
                      error_message=None, details=None):
    cur = conn.cursor()
    cur.execute("""
        UPDATE erp_sync_logs
        SET status = %s, records_processed = %s, records_failed = %s,
            error_message = %s, details = COALESCE(details, '{}'::jsonb) || COALESCE(%s, '{}'::jsonb),
            completed_at = NOW()
        WHERE id = %s
    """, (status, records_processed, records_failed, error_message, details, log_id))
    conn.commit()
    cur.close()


# ─── Generic Sync Runner ─────────────────────────────

def run_sync(conn, config_id, sync_type='full'):
    """Run a sync job for a configured ERP.

    This is the main entry point. It looks up the config, instantiates
    the appropriate handler, and executes the sync.
    """
    cur = conn.cursor()
    cur.execute("SELECT erp_type, tenant_id FROM erp_sync_configs WHERE id = %s", (config_id,))
    row = cur.fetchone()
    cur.close()
    if not row:
        raise ValueError(f"Sync config {config_id} not found")

    erp_type, tenant_id = row
    handler_class = get_erp_handler(erp_type)

    if not handler_class:
        log_sync_run(conn, config_id, sync_type, 'to_erp', 'failed',
                     error_message=f"No handler registered for ERP type: {erp_type}")
        return {'status': 'failed', 'error': f'No handler for {erp_type}'}

    handler = handler_class(conn, config_id, tenant_id)
    return handler.sync(sync_type)


# ─── Base ERP Handler Class ─────────────────────────────

class BaseERPHandler:
    """Base class for ERP-specific sync handlers."""

    def __init__(self, conn, config_id, tenant_id):
        self.conn = conn
        self.config_id = config_id
        self.tenant_id = tenant_id

    def sync(self, sync_type):
        raise NotImplementedError

    def sync_inventory_to_erp(self):
        raise NotImplementedError

    def sync_inventory_from_erp(self):
        raise NotImplementedError

    def sync_sales_to_erp(self):
        raise NotImplementedError

    def sync_customers_to_erp(self):
        raise NotImplementedError

    def sync_customers_from_erp(self):
        raise NotImplementedError


# ─── Aspel SAE Stub ─────────────────────────────

class AspelSAEHandler(BaseERPHandler):
    """Stub for Aspel SAE sync.

    Aspel SAE is a desktop ERP. Integration options:
    1. ODBC direct to the SQL Server / Interbase database
    2. Aspel REST API (via Aspel NOI middleware)
    3. File-based sync (CSV/XML export/import)

    Recommended: Option 2 (REST API) if available, else Option 3.
    """

    def sync(self, sync_type):
        log_id = log_sync_run(self.conn, self.config_id, sync_type, 'bidirectional', 'running')

        # Stub: would call Aspel API here
        complete_sync_run(
            self.conn, log_id, 'failed', 0, 0,
            error_message='Aspel SAE handler not implemented. Requires Aspel REST API or ODBC connection.',
            details={'message': 'Stub implementation. Activate when Aspel credentials are available.'}
        )
        return {'status': 'failed', 'error': 'Aspel SAE handler not implemented'}


# ─── Contpaqi Stub ─────────────────────────────

class ContpaqiHandler(BaseERPHandler):
    """Stub for Contpaqi sync.

    Contpaqi integration options:
    1. Contpaqi SDK (COM/ActiveX on Windows)
    2. Contpaqi REST API (via middleware like Facturama)
    3. Direct database access to Firebird/Interbase

    Recommended: Option 2 for cloud deployments.
    """

    def sync(self, sync_type):
        log_id = log_sync_run(self.conn, self.config_id, sync_type, 'bidirectional', 'running')

        complete_sync_run(
            self.conn, log_id, 'failed', 0, 0,
            error_message='Contpaqi handler not implemented. Requires Contpaqi SDK or REST middleware.',
            details={'message': 'Stub implementation. Activate when Contpaqi credentials are available.'}
        )
        return {'status': 'failed', 'error': 'Contpaqi handler not implemented'}


# ─── SAP B1 Stub ─────────────────────────────

class SAPB1Handler(BaseERPHandler):
    """Stub for SAP Business One sync.

    SAP B1 provides a Service Layer REST API (OData-based).
    Requires: Service Layer URL, Company DB, username, password.
    """

    def sync(self, sync_type):
        log_id = log_sync_run(self.conn, self.config_id, sync_type, 'bidirectional', 'running')

        complete_sync_run(
            self.conn, log_id, 'failed', 0, 0,
            error_message='SAP B1 handler not implemented. Requires Service Layer endpoint.',
            details={'message': 'Stub implementation. Activate when SAP B1 Service Layer is available.'}
        )
        return {'status': 'failed', 'error': 'SAP B1 handler not implemented'}


# ─── Odoo Stub ─────────────────────────────

class OdooHandler(BaseERPHandler):
    """Stub for Odoo sync.

    Odoo provides XML-RPC and JSON-RPC APIs.
    Requires: URL, database name, username, API key.
    """

    def sync(self, sync_type):
        log_id = log_sync_run(self.conn, self.config_id, sync_type, 'bidirectional', 'running')

        complete_sync_run(
            self.conn, log_id, 'failed', 0, 0,
            error_message='Odoo handler not implemented. Requires Odoo URL and API credentials.',
            details={'message': 'Stub implementation. Activate when Odoo credentials are available.'}
        )
        return {'status': 'failed', 'error': 'Odoo handler not implemented'}


# Register handlers
register_erp_handler('aspel_sae', AspelSAEHandler)
register_erp_handler('contpaqi', ContpaqiHandler)
register_erp_handler('sap_b1', SAPB1Handler)
register_erp_handler('odoo', OdooHandler)