"""
Fig 6: CPL Avalanche Loop Diagram
Shows the positive feedback mechanism in CPL discharge
"""

import os
from graphviz import Digraph

def make_figure(config):
    """Generate Fig 6: CPL Avalanche Loop"""
    
    dot = Digraph(comment='CPL Avalanche Loop')
    dot.attr(rankdir='LR', size='10,6')
    dot.attr('node', fontname='Times New Roman', fontsize='11', style='filled')
    dot.attr('edge', fontname='Times New Roman', fontsize='10')
    
    # Main feedback loop nodes
    dot.node('V', 'Terminal Voltage\nDecreases\n(V_term ↓)', 
             shape='box', fillcolor='#ffcccc', width='2')
    
    dot.node('I', 'Current\nIncreases\n(I ↑)', 
             shape='box', fillcolor='#ffffcc', width='2')
    
    dot.node('Loss', 'Joule Loss\nIncreases\n(I²R₀ ↑)', 
             shape='box', fillcolor='#ffddaa', width='2')
    
    dot.node('Heat', 'Temperature\nRises\n(T_b ↑)', 
             shape='box', fillcolor='#ffaa99', width='2')
    
    dot.node('R', 'Resistance\nIncreases\n(R₀ ↑)', 
             shape='box', fillcolor='#ff9999', width='2')
    
    # CPL constraint node
    dot.node('CPL', 'CPL Constraint\nP = I × V_term\n(constant)', 
             shape='ellipse', fillcolor='lightblue', width='2.5', height='1.2')
    
    # SOC depletion
    dot.node('SOC', 'SOC Depletes\n(z ↓)', 
             shape='box', fillcolor='#ccccff', width='2')
    
    # Main feedback edges
    dot.edge('V', 'I', label='CPL:\nP=constant', color='red', penwidth='2')
    dot.edge('I', 'Loss', label='Quadratic', color='darkred', penwidth='2')
    dot.edge('Loss', 'Heat', label='Thermal', color='orange', penwidth='1.5')
    dot.edge('Heat', 'R', label='Arrhenius', color='orange', penwidth='1.5')
    dot.edge('R', 'V', label='V_term = V_oc - IR₀', color='red', penwidth='2')
    
    # SOC impact
    dot.edge('I', 'SOC', label='Discharge\nrate', color='blue', penwidth='1.5')
    dot.edge('SOC', 'V', label='V_oc(z)', color='blue', penwidth='1.5')
    dot.edge('SOC', 'R', label='R₀(z)', color='blue', penwidth='1.5', style='dashed')
    
    # CPL connection
    dot.edge('CPL', 'I', style='dashed', color='gray')
    dot.edge('V', 'CPL', style='dashed', color='gray')
    
    # Add legend
    with dot.subgraph(name='cluster_legend') as c:
        c.attr(label='Loop Characteristics', style='dashed', fontsize='10')
        c.node('L1', '• Positive Feedback (Runaway)\n' +
                    '• Accelerates near end of discharge\n' +
                    '• Non-linear TTE relationship\n' +
                    '• Temperature coupling critical',
               shape='note', fillcolor='lightyellow', fontsize='9')
    
    # Output directory
    figure_dir = config.get('global', {}).get('figure_dir', 'figures')
    os.makedirs(figure_dir, exist_ok=True)
    
    # Render
    output_base = os.path.join(figure_dir, 'Fig06_CPL_Avalanche')
    dot.render(output_base, format='pdf', cleanup=True)
    dot.render(output_base, format='png', cleanup=True)
    
    return {
        "output_files": [f"{output_base}.pdf", f"{output_base}.png"],
        "computed_metrics": {},
        "validation_flags": {},
        "pass": True
    }