Refactor calculation logic into modular package structure

aca_calc/__init__.py

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+"""ACA Premium Tax Credit Calculator."""
+
+__version__ = "0.1.0"

aca_calc/calculations/__init__.py

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+"""ACA Calculator calculation modules."""
+
+from aca_calc.calculations.household import build_household_situation
+
+__all__ = ["build_household_situation"]

aca_calc/calculations/charts.py

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+"""Chart creation functions for ACA calculator."""
+
+import numpy as np
+import plotly.graph_objects as go
+from policyengine_us import Simulation
+
+from aca_calc.calculations.household import build_household_situation
+from aca_calc.calculations.reforms import create_enhanced_ptc_reform
+
+
+# PolicyEngine brand colors
+COLORS = {
+    "primary": "#2C6496",
+    "secondary": "#39C6C0",
+    "green": "#28A745",
+    "gray": "#BDBDBD",
+    "blue_gradient": ["#D1E5F0", "#92C5DE", "#2166AC", "#053061"],
+}
+
+
+def add_logo_to_layout():
+    """Add PolicyEngine logo to chart layout."""
+    import base64
+
+    try:
+        with open("blue.png", "rb") as f:
+            logo_base64 = base64.b64encode(f.read()).decode()
+            return {
+                "images": [
+                    {
+                        "source": f"data:image/png;base64,{logo_base64}",
+                        "xref": "paper",
+                        "yref": "paper",
+                        "x": 1.01,
+                        "y": -0.18,
+                        "sizex": 0.10,
+                        "sizey": 0.10,
+                        "xanchor": "right",
+                        "yanchor": "bottom",
+                    }
+                ]
+            }
+    except:
+        return {}
+
+
+def create_ptc_charts(
+    age_head,
+    age_spouse,
+    dependent_ages,
+    state,
+    county=None,
+    zip_code=None,
+    income=None,
+):
+    """Create PTC comparison and difference charts.
+
+    Args:
+        age_head: Age of head of household
+        age_spouse: Age of spouse (None if not married)
+        dependent_ages: List/tuple of dependent ages
+        state: Two-letter state code
+        county: County name
+        zip_code: 5-digit ZIP code
+        income: Optional income to mark on chart
+
+    Returns:
+        tuple: (comparison_fig, delta_fig, benefit_info, income_range,
+                ptc_baseline_range, ptc_reform_range, slcsp, fpl, x_axis_max)
+    """
+    # Convert tuple to list for household builder
+    dependent_ages = list(dependent_ages) if dependent_ages else []
+
+    # Build household with axes
+    base_household = build_household_situation(
+        age_head=age_head,
+        age_spouse=age_spouse,
+        dependent_ages=dependent_ages,
+        state=state,
+        county=county,
+        zip_code=zip_code,
+        year=2026,
+        with_axes=True,
+    )
+
+    try:
+        reform = create_enhanced_ptc_reform()
+
+        # Run simulations
+        sim_baseline = Simulation(situation=base_household)
+        sim_reform = Simulation(situation=base_household, reform=reform)
+
+        income_range = sim_baseline.calculate(
+            "employment_income", map_to="household", period=2026
+        )
+        ptc_range_baseline = sim_baseline.calculate(
+            "aca_ptc", map_to="household", period=2026
+        )
+        ptc_range_reform = sim_reform.calculate(
+            "aca_ptc", map_to="household", period=2026
+        )
+
+        # Calculate Medicaid and CHIP
+        medicaid_range = sim_baseline.calculate(
+            "medicaid_cost", map_to="household", period=2026
+        )
+        chip_range = sim_baseline.calculate(
+            "per_capita_chip", map_to="household", period=2026
+        )
+
+        # Find x-axis range
+        max_income_with_ptc = 200000
+        for i in range(len(ptc_range_reform) - 1, -1, -1):
+            if ptc_range_reform[i] > 0:
+                max_income_with_ptc = income_range[i]
+                break
+        x_axis_max = min(1000000, max_income_with_ptc * 1.1)
+
+        delta_range = ptc_range_reform - ptc_range_baseline
+
+        # TODO: Implement full chart creation
+        # For now, return None to keep refactoring incremental
+        return None, None, None, income_range, ptc_range_baseline, ptc_range_reform, 0, 0, x_axis_max
+
+    except Exception as e:
+        raise Exception(f"Chart creation error: {str(e)}") from e

aca_calc/calculations/household.py

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+"""
+Household situation building utilities for PolicyEngine simulations.
+"""
+
+
+def build_household_situation(
+    age_head,
+    age_spouse,
+    dependent_ages,
+    state,
+    county=None,
+    zip_code=None,
+    year=2026,
+    with_axes=False,
+):
+    """Build a PolicyEngine household situation.
+
+    Args:
+        age_head: Age of head of household
+        age_spouse: Age of spouse (None if not married)
+        dependent_ages: List of dependent ages
+        state: Two-letter state code (e.g., "CA")
+        county: County name (e.g., "Los Angeles County")
+        zip_code: 5-digit ZIP code (required for LA County)
+        year: Year for simulation
+        with_axes: If True, add employment_income axis for income sweep
+
+    Returns:
+        dict: PolicyEngine situation dictionary
+    """
+    situation = {
+        "people": {"you": {"age": {year: age_head}}},
+        "families": {"your family": {"members": ["you"]}},
+        "spm_units": {"your household": {"members": ["you"]}},
+        "tax_units": {"your tax unit": {"members": ["you"]}},
+        "households": {
+            "your household": {"members": ["you"], "state_name": {year: state}}
+        },
+    }
+
+    # Add axes if requested (for income sweeps)
+    if with_axes:
+        situation["axes"] = [
+            [
+                {
+                    "name": "employment_income",
+                    "count": 10_001,
+                    "min": 0,
+                    "max": 1000000,
+                    "period": year,
+                }
+            ]
+        ]
+
+    # Add county if provided
+    if county:
+        county_pe_format = county.upper().replace(" ", "_") + "_" + state
+        situation["households"]["your household"]["county"] = {
+            year: county_pe_format
+        }
+
+    # Add ZIP code if provided (required for LA County)
+    if zip_code:
+        situation["households"]["your household"]["zip_code"] = {year: zip_code}
+
+    # Add spouse if married
+    if age_spouse:
+        situation["people"]["your partner"] = {"age": {year: age_spouse}}
+        situation["families"]["your family"]["members"].append("your partner")
+        situation["spm_units"]["your household"]["members"].append("your partner")
+        situation["tax_units"]["your tax unit"]["members"].append("your partner")
+        situation["households"]["your household"]["members"].append("your partner")
+        situation["marital_units"] = {
+            "your marital unit": {"members": ["you", "your partner"]}
+        }
+
+    # Add dependents
+    for i, dep_age in enumerate(dependent_ages):
+        if i == 0:
+            child_id = "your first dependent"
+        elif i == 1:
+            child_id = "your second dependent"
+        else:
+            child_id = f"dependent_{i+1}"
+
+        situation["people"][child_id] = {"age": {year: dep_age}}
+        situation["families"]["your family"]["members"].append(child_id)
+        situation["spm_units"]["your household"]["members"].append(child_id)
+        situation["tax_units"]["your tax unit"]["members"].append(child_id)
+        situation["households"]["your household"]["members"].append(child_id)
+
+        # Add child's marital unit
+        if "marital_units" not in situation:
+            situation["marital_units"] = {}
+        situation["marital_units"][f"{child_id}'s marital unit"] = {
+            "members": [child_id]
+        }
+
+    return situation

aca_calc/calculations/ptc.py

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+"""Premium Tax Credit calculation functions."""
+
+import copy
+from policyengine_us import Simulation
+
+from aca_calc.calculations.household import build_household_situation
+from aca_calc.calculations.reforms import create_enhanced_ptc_reform
+
+
+def calculate_ptc(
+    age_head,
+    age_spouse,
+    income,
+    dependent_ages,
+    state,
+    county_name=None,
+    zip_code=None,
+    use_reform=False,
+):
+    """Calculate PTC for baseline or IRA enhanced scenario using 2026 comparison.
+
+    Args:
+        age_head: Age of head of household
+        age_spouse: Age of spouse (None if not married)
+        income: Annual household income
+        dependent_ages: List of dependent ages
+        state: Two-letter state code
+        county_name: County name (e.g., "Travis County")
+        zip_code: 5-digit ZIP code (required for LA County)
+        use_reform: If True, use enhanced PTC reform
+
+    Returns:
+        tuple: (ptc, slcsp, fpl, fpl_pct)
+    """
+    try:
+        # Build base household situation
+        situation = build_household_situation(
+            age_head=age_head,
+            age_spouse=age_spouse,
+            dependent_ages=dependent_ages,
+            state=state,
+            county=county_name,
+            zip_code=zip_code,
+            year=2026,
+            with_axes=False,
+        )
+
+        # Deep copy and inject income
+        sit = copy.deepcopy(situation)
+
+        # Split income between adults if married
+        if age_spouse:
+            sit["people"]["you"]["employment_income"] = {2026: income / 2}
+            sit["people"]["your partner"]["employment_income"] = {
+                2026: income / 2
+            }
+        else:
+            sit["people"]["you"]["employment_income"] = {2026: income}
+
+        # Create reform if requested
+        reform = create_enhanced_ptc_reform() if use_reform else None
+
+        # Run simulation
+        sim = Simulation(situation=sit, reform=reform)
+
+        ptc = sim.calculate("aca_ptc", map_to="household", period=2026)[0]
+        slcsp = sim.calculate("slcsp", map_to="household", period=2026)[0]
+        fpl = sim.calculate("tax_unit_fpg", period=2026)[0]
+        aca_magi_fraction = sim.calculate("aca_magi_fraction", period=2026)[0]
+        fpl_pct = aca_magi_fraction * 100
+
+        return float(max(0, ptc)), float(slcsp), float(fpl), float(fpl_pct)
+
+    except Exception as e:
+        raise Exception(f"PTC calculation error: {str(e)}") from e

aca_calc/calculations/reforms.py

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+"""PolicyEngine reform definitions for ACA scenarios."""
+
+from policyengine_core.reforms import Reform
+
+
+def create_enhanced_ptc_reform():
+    """Create reform extending enhanced PTCs through 2026.
+
+    Returns:
+        Reform: PolicyEngine reform object
+    """
+    return Reform.from_dict(
+        {
+            "gov.aca.ptc_phase_out_rate[0].amount": {
+                "2026-01-01.2100-12-31": 0
+            },
+            "gov.aca.ptc_phase_out_rate[1].amount": {
+                "2025-01-01.2100-12-31": 0
+            },
+            "gov.aca.ptc_phase_out_rate[2].amount": {
+                "2026-01-01.2100-12-31": 0
+            },
+            "gov.aca.ptc_phase_out_rate[3].amount": {
+                "2026-01-01.2100-12-31": 0.02
+            },
+            "gov.aca.ptc_phase_out_rate[4].amount": {
+                "2026-01-01.2100-12-31": 0.04
+            },
+            "gov.aca.ptc_phase_out_rate[5].amount": {
+                "2026-01-01.2100-12-31": 0.06
+            },
+            "gov.aca.ptc_phase_out_rate[6].amount": {
+                "2026-01-01.2100-12-31": 0.085
+            },
+            "gov.aca.ptc_income_eligibility[2].amount": {
+                "2026-01-01.2100-12-31": True
+            },
+        },
+        country_id="us",
+    )