Hi,

You can create the Python code like:

from odoo import models, fields, api

class WarehouseSalesReport(models.TransientModel):
    _name = 'custom_reports.warehouse_sales_report'
    _description = 'Warehouse Sales Report'

    start_date = fields.Date('Start Date', required=True)
    end_date = fields.Date('End Date', required=True)

    @api.multi
    def generate_report_data(self):
        # Fetch and process data based on the selected date range
        # you can add the condition and other details

        # Return a dictionary with data needed for the report
        return {
            'products': [
                {'name': 'Product 1', 'opening_stock': 10, 'closing_stock': 5, 'cost_price': 15.0, 'selling_price': 20.0},
                # Add the date with your specified requirements
            ],
            'total_amount': 5000.0,
        }

XML :

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>
        <!-- Action to call the report -->
<record id="action_report_warehouse_sales" model="ir.actions.server">
            <field name="name">Generate Warehouse Sales Report</field>
<field name="type">ir.actions.server</field>
<field name="model_id" ref="model_custom_reports_warehouse_sales_report"/>
            <field name="state">code</field>
            <field name="code">action = generate_report_data()</field>
        </record>

        <!-- Menu item to trigger the report action -->
<menuitem id="menu_report_warehouse_sales" name="Warehouse Sales Report" parent="menu_custom_reports" sequence="10"/>
<menuitem id="menu_action_report_warehouse_sales" name="Generate Report" parent="menu_report_warehouse_sales" action="action_report_warehouse_sales"/>
    </data>
</odoo>

for reports:  

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<template id="report_warehouse_sales_template">
        <t t-call="web.html_container">
            <t t-foreach="data['products']" t-as="product">
                <div>
                    <p><t t-esc="product['name']"/></p>
<p>Opening Stock: <t t-esc="product['opening_stock']"/></p>
<p>Closing Stock: <t t-esc="product['closing_stock']"/></p>
<p>Cost Price: <t t-esc="product['cost_price']"/></p>
<p>Selling Price: <t t-esc="product['selling_price']"/></p>
                </div>
            </t>
            <div>
<p>Total Amount: <t t-esc="data['total_amount']"/></p>
            </div>
        </t>
    </template>
</odoo>

Hope it helps