"""
Export service for inventory snapshot and audit trail exports.
Supports CSV and Excel (.xlsx) formats.
"""

import csv
import io
from datetime import datetime
from typing import List, Optional
from openpyxl import Workbook
from openpyxl.styles import Font, PatternFill, Alignment
from openpyxl.utils import get_column_letter


class InventorySnapshotExporter:
    """Export inventory items to CSV or Excel format."""

    HEADERS = [
        "ID",
        "Name",
        "Part Number",
        "Barcode",
        "Category",
        "Type",
        "Quantity",
        "Min Quantity",
        "Description",
        "Color",
        "Size",
        "Connector",
        "Box Label",
        "Created",
        "Modified",
    ]

    @staticmethod
    def _item_to_row(item) -> list:
        """Convert Item object to row data."""
        return [
            item.id,
            item.name or "",
            item.part_number or "",
            item.barcode or "",
            item.category or "",
            item.type or "",
            str(item.quantity or 0),
            str(item.min_quantity or 1),
            item.description or "",
            item.color or "",
            item.size or "",
            item.connector or "",
            item.box_label or "",
            item.created_at.isoformat() if hasattr(item, "created_at") and item.created_at else "",
            item.updated_at.isoformat() if hasattr(item, "updated_at") and item.updated_at else "",
        ]

    @classmethod
    def to_csv(cls, items: List, timestamp: str) -> str:
        """
        Export items to CSV format.

        Args:
            items: List of Item objects
            timestamp: ISO 8601 date string (YYYY-MM-DD)

        Returns:
            CSV string content
        """
        output = io.StringIO()
        writer = csv.writer(output, quoting=csv.QUOTE_MINIMAL)

        # Write header
        writer.writerow(cls.HEADERS)

        # Write data rows
        for item in items:
            writer.writerow(cls._item_to_row(item))

        return output.getvalue()

    @classmethod
    def to_excel(cls, items: List, timestamp: str) -> bytes:
        """
        Export items to Excel (.xlsx) format.

        Args:
            items: List of Item objects
            timestamp: ISO 8601 date string (YYYY-MM-DD)

        Returns:
            Bytes containing Excel file content
        """
        wb = Workbook()
        ws = wb.active
        ws.title = "Inventory Snapshot"

        # Add title row
        ws.append([f"Inventory Snapshot - {timestamp}"])
        title_cell = ws["A1"]
        title_cell.font = Font(bold=False, size=12)
        title_cell.fill = PatternFill(start_color="E8F4F8", end_color="E8F4F8", fill_type="solid")
        ws.merge_cells("A1:O1")

        # Add headers
        ws.append(cls.HEADERS)
        header_fill = PatternFill(start_color="D3D3D3", end_color="D3D3D3", fill_type="solid")
        header_font = Font(bold=False)
        for cell in ws[2]:
            cell.fill = header_fill
            cell.font = header_font
            cell.alignment = Alignment(horizontal="center", vertical="center")

        # Add data rows
        for item in items:
            ws.append(cls._item_to_row(item))

        # Adjust column widths
        column_widths = [8, 20, 15, 15, 15, 12, 10, 12, 20, 12, 10, 15, 15, 20, 20]
        for i, width in enumerate(column_widths, 1):
            ws.column_dimensions[get_column_letter(i)].width = width

        # Center align quantity columns
        for row in ws.iter_rows(min_row=3, max_row=ws.max_row, min_col=7, max_col=8):
            for cell in row:
                cell.alignment = Alignment(horizontal="right")

        # Convert to bytes
        output = io.BytesIO()
        wb.save(output)
        output.seek(0)
        return output.getvalue()


class AuditTrailExporter:
    """Export audit logs to CSV or Excel format."""

    HEADERS = [
        "ID",
        "Timestamp",
        "User",
        "Action",
        "Item ID",
        "Item Name",
        "Item Part Number",
        "Item Barcode",
        "Quantity Change",
        "Details",
    ]

    @staticmethod
    def _log_to_row(log) -> list:
        """Convert AuditLog object to row data."""
        user_name = log.user.username if (hasattr(log, "user") and log.user) else ""
        return [
            log.id,
            log.timestamp.isoformat() if log.timestamp else "",
            user_name,
            log.action or "",
            log.target_item_id or "",
            log.target_item_name or "",
            log.target_item_pn or "",
            log.target_item_barcode or "",
            str(log.quantity_change or ""),
            log.details or "",
        ]

    @classmethod
    def to_csv(cls, logs: List, timestamp: str) -> str:
        """
        Export audit logs to CSV format.

        Args:
            logs: List of AuditLog objects
            timestamp: ISO 8601 date string (YYYY-MM-DD)

        Returns:
            CSV string content
        """
        output = io.StringIO()
        writer = csv.writer(output, quoting=csv.QUOTE_MINIMAL)

        # Write header
        writer.writerow(cls.HEADERS)

        # Write data rows
        for log in logs:
            writer.writerow(cls._log_to_row(log))

        return output.getvalue()

    @classmethod
    def to_excel(cls, logs: List, timestamp: str) -> bytes:
        """
        Export audit logs to Excel (.xlsx) format.

        Args:
            logs: List of AuditLog objects
            timestamp: ISO 8601 date string (YYYY-MM-DD)

        Returns:
            Bytes containing Excel file content
        """
        wb = Workbook()
        ws = wb.active
        ws.title = "Audit Trail"

        # Add title row
        ws.append([f"Audit Trail - {timestamp}"])
        title_cell = ws["A1"]
        title_cell.font = Font(bold=False, size=12)
        title_cell.fill = PatternFill(start_color="E8F4F8", end_color="E8F4F8", fill_type="solid")
        ws.merge_cells("A1:J1")

        # Add headers
        ws.append(cls.HEADERS)
        header_fill = PatternFill(start_color="D3D3D3", end_color="D3D3D3", fill_type="solid")
        header_font = Font(bold=False)
        for cell in ws[2]:
            cell.fill = header_fill
            cell.font = header_font
            cell.alignment = Alignment(horizontal="center", vertical="center")

        # Add data rows
        for log in logs:
            ws.append(cls._log_to_row(log))

        # Adjust column widths
        column_widths = [8, 25, 15, 15, 10, 20, 18, 15, 15, 30]
        for i, width in enumerate(column_widths, 1):
            ws.column_dimensions[get_column_letter(i)].width = width

        # Right-align quantity change
        for row in ws.iter_rows(min_row=3, max_row=ws.max_row, min_col=9, max_col=9):
            for cell in row:
                cell.alignment = Alignment(horizontal="right")

        # Convert to bytes
        output = io.BytesIO()
        wb.save(output)
        output.seek(0)
        return output.getvalue()


def get_export_filename(report_type: str, format_type: str, timestamp: str) -> str:
    """
    Generate export filename with timestamp.

    Args:
        report_type: 'inventory_snapshot' or 'audit_trail'
        format_type: 'csv' or 'xlsx'
        timestamp: ISO 8601 date string (YYYY-MM-DD)

    Returns:
        Filename string (e.g., 'inventory_snapshot_2026-04-22.csv')
    """
    extension = "csv" if format_type == "csv" else "xlsx"
    return f"{report_type}_{timestamp}.{extension}"