cost-estimation-resource

# Cost Estimation - Resource Method

## Business Case

### Problem Statement
Traditional costing challenges:
- Fixed unit prices become outdated
- No visibility into cost components
- Difficult to adjust for conditions
- Limited cost analysis capability

### Solution
Resource-based costing separates physical resource consumption (norms) from prices, enabling accurate, adjustable, and transparent cost estimation.

## Technical Implementation

```python
import pandas as pd
from typing import Dict, Any, List, Optional
from dataclasses import dataclass, field
from enum import Enum


class ResourceType(Enum):
    LABOR = "labor"
    MATERIAL = "material"
    EQUIPMENT = "equipment"
    SUBCONTRACTOR = "subcontractor"


@dataclass
class Resource:
    code: str
    name: str
    resource_type: ResourceType
    unit: str
    unit_price: float
    currency: str = "USD"


@dataclass
class ResourceNorm:
    resource_code: str
    consumption: float  # Units per work item unit
    waste_factor: float = 1.0  # 1.1 = 10% waste


@dataclass
class WorkItem:
    code: str
    name: str
    unit: str
    resources: List[ResourceNorm] = field(default_factory=list)


@dataclass
class CostLineItem:
    work_item_code: str
    work_item_name: str
    quantity: float
    unit: str
    labor_cost: float
    material_cost: float
    equipment_cost: float
    subcontractor_cost: float
    total_cost: float


class ResourceBasedEstimator:
    """Calculate costs using resource-based method."""

    def __init__(self):
        self.resources: Dict[str, Resource] = {}
        self.work_items: Dict[str, WorkItem] = {}
        self.overhead_rate: float = 0.15
        self.profit_rate: float = 0.10

    def add_resource(self, resource: Resource):
        """Add resource to database."""
        self.resources[resource.code] = resource

    def add_work_item(self, work_item: WorkItem):
        """Add work item with reso...