import { create } from 'zustand';
import { Node, Edge, addEdge, applyNodeChanges, applyEdgeChanges, Connection, NodeChange, EdgeChange } from 'reactflow';
import { CanvasNodeData, NodeType } from '../lib/canvas/schema';
import { validateGraph, ValidationResult } from '../lib/canvas/validation';
import { serializeToIntent, OptimizationIntent } from '../lib/canvas/intent';

interface CanvasState {
  nodes: Node<CanvasNodeData>[];
  edges: Edge[];
  selectedNode: string | null;
  validation: ValidationResult;

  // Actions
  onNodesChange: (changes: NodeChange[]) => void;
  onEdgesChange: (changes: EdgeChange[]) => void;
  onConnect: (connection: Connection) => void;
  addNode: (type: NodeType, position: { x: number; y: number }) => void;
  updateNodeData: (nodeId: string, data: Partial<CanvasNodeData>) => void;
  selectNode: (nodeId: string | null) => void;
  deleteSelected: () => void;
  validate: () => ValidationResult;
  toIntent: () => OptimizationIntent;
  clear: () => void;
  loadFromIntent: (intent: OptimizationIntent) => void;
  loadFromConfig: (config: OptimizationConfig) => void;
}

// Optimization config structure (from optimization_config.json)
export interface OptimizationConfig {
  study_name?: string;
  model?: {
    path?: string;
    type?: string;
  };
  solver?: {
    type?: string;
    solution?: number;
  };
  design_variables?: Array<{
    name: string;
    expression_name?: string;
    lower: number;
    upper: number;
    type?: string;
  }>;
  objectives?: Array<{
    name: string;
    direction?: string;
    weight?: number;
    extractor?: string;
  }>;
  constraints?: Array<{
    name: string;
    type?: string;
    value?: number;
    extractor?: string;
  }>;
  method?: string;
  max_trials?: number;
  surrogate?: {
    type?: string;
    min_trials?: number;
  } | null;
}

let nodeIdCounter = 0;
const getNodeId = () => `node_${++nodeIdCounter}`;

const getDefaultData = (type: NodeType): CanvasNodeData => {
  const base = { label: type.charAt(0).toUpperCase() + type.slice(1), configured: false };

  switch (type) {
    case 'model': return { ...base, type: 'model' };
    case 'solver': return { ...base, type: 'solver' };
    case 'designVar': return { ...base, type: 'designVar', label: 'Design Variable' };
    case 'extractor': return { ...base, type: 'extractor' };
    case 'objective': return { ...base, type: 'objective' };
    case 'constraint': return { ...base, type: 'constraint' };
    case 'algorithm': return { ...base, type: 'algorithm' };
    case 'surrogate': return { ...base, type: 'surrogate', enabled: false };
    default: return { ...base, type } as CanvasNodeData;
  }
};

// Layout constants for auto-arrangement
const LAYOUT = {
  startX: 100,
  startY: 100,
  colWidth: 250,
  rowHeight: 120,
};

export const useCanvasStore = create<CanvasState>((set, get) => ({
  nodes: [],
  edges: [],
  selectedNode: null,
  validation: { valid: false, errors: [], warnings: [] },

  onNodesChange: (changes) => {
    set({ nodes: applyNodeChanges(changes, get().nodes) });
  },

  onEdgesChange: (changes) => {
    set({ edges: applyEdgeChanges(changes, get().edges) });
  },

  onConnect: (connection) => {
    set({ edges: addEdge(connection, get().edges) });
  },

  addNode: (type, position) => {
    const newNode: Node<CanvasNodeData> = {
      id: getNodeId(),
      type,
      position,
      data: getDefaultData(type),
    };
    set({ nodes: [...get().nodes, newNode] });
  },

  updateNodeData: (nodeId, data) => {
    set({
      nodes: get().nodes.map((node) =>
        node.id === nodeId
          ? { ...node, data: { ...node.data, ...data } }
          : node
      ),
    });
  },

  selectNode: (nodeId) => {
    set({ selectedNode: nodeId });
  },

  deleteSelected: () => {
    const { selectedNode, nodes, edges } = get();
    if (!selectedNode) return;

    set({
      nodes: nodes.filter((n) => n.id !== selectedNode),
      edges: edges.filter((e) => e.source !== selectedNode && e.target !== selectedNode),
      selectedNode: null,
    });
  },

  validate: () => {
    const { nodes, edges } = get();
    const result = validateGraph(nodes, edges);
    set({ validation: result });
    return result;
  },

  toIntent: () => {
    const { nodes, edges } = get();
    return serializeToIntent(nodes, edges);
  },

  clear: () => {
    set({
      nodes: [],
      edges: [],
      selectedNode: null,
      validation: { valid: false, errors: [], warnings: [] },
    });
    nodeIdCounter = 0;
  },

  loadFromIntent: (intent) => {
    // Clear existing
    nodeIdCounter = 0;
    const nodes: Node<CanvasNodeData>[] = [];
    const edges: Edge[] = [];

    let col = 0;
    let row = 0;

    // Helper to create positioned node
    const createNode = (type: NodeType, data: Partial<CanvasNodeData>, colOffset = 0): string => {
      const id = getNodeId();
      nodes.push({
        id,
        type,
        position: {
          x: LAYOUT.startX + (col + colOffset) * LAYOUT.colWidth,
          y: LAYOUT.startY + row * LAYOUT.rowHeight,
        },
        data: { ...getDefaultData(type), ...data, configured: true } as CanvasNodeData,
      });
      return id;
    };

    // Model node (column 0)
    col = 0;
    const modelId = createNode('model', {
      label: 'Model',
      filePath: intent.model?.path,
      fileType: intent.model?.type as 'prt' | 'fem' | 'sim' | undefined,
    });

    // Solver node (column 1)
    col = 1;
    const solverId = createNode('solver', {
      label: 'Solver',
      solverType: intent.solver?.type as any,
    });
    edges.push({ id: `e_${modelId}_${solverId}`, source: modelId, target: solverId });

    // Design variables (column 0, multiple rows)
    col = 0;
    row = 1;
    const dvIds: string[] = [];
    for (const dv of intent.design_variables || []) {
      const dvId = createNode('designVar', {
        label: dv.name,
        expressionName: dv.name,
        minValue: dv.min,
        maxValue: dv.max,
        unit: dv.unit,
      });
      dvIds.push(dvId);
      edges.push({ id: `e_${dvId}_${modelId}`, source: dvId, target: modelId });
      row++;
    }

    // Extractors (column 2)
    col = 2;
    row = 0;
    const extractorMap: Record<string, string> = {};
    for (const ext of intent.extractors || []) {
      const extId = createNode('extractor', {
        label: ext.name,
        extractorId: ext.id,
        extractorName: ext.name,
        config: ext.config,
      });
      extractorMap[ext.id] = extId;
      edges.push({ id: `e_${solverId}_${extId}`, source: solverId, target: extId });
      row++;
    }

    // Objectives (column 3)
    col = 3;
    row = 0;
    const objIds: string[] = [];
    for (const obj of intent.objectives || []) {
      const objId = createNode('objective', {
        label: obj.name,
        name: obj.name,
        direction: obj.direction,
        weight: obj.weight,
      });
      objIds.push(objId);
      // Connect to extractor if specified
      if (obj.extractor && extractorMap[obj.extractor]) {
        edges.push({ id: `e_${extractorMap[obj.extractor]}_${objId}`, source: extractorMap[obj.extractor], target: objId });
      }
      row++;
    }

    // Constraints (column 3, after objectives)
    const conIds: string[] = [];
    for (const con of intent.constraints || []) {
      const conId = createNode('constraint', {
        label: con.name,
        name: con.name,
        operator: con.operator as any,
        value: con.value,
      });
      conIds.push(conId);
      if (con.extractor && extractorMap[con.extractor]) {
        edges.push({ id: `e_${extractorMap[con.extractor]}_${conId}`, source: extractorMap[con.extractor], target: conId });
      }
      row++;
    }

    // Algorithm (column 4)
    col = 4;
    row = 0;
    const algoId = createNode('algorithm', {
      label: 'Algorithm',
      method: intent.optimization?.method as any,
      maxTrials: intent.optimization?.max_trials,
    });
    // Connect all objectives and constraints to algorithm
    for (const objId of objIds) {
      edges.push({ id: `e_${objId}_${algoId}`, source: objId, target: algoId });
    }
    for (const conId of conIds) {
      edges.push({ id: `e_${conId}_${algoId}`, source: conId, target: algoId });
    }

    // Surrogate (column 5, optional)
    if (intent.surrogate?.enabled) {
      col = 5;
      const surId = createNode('surrogate', {
        label: 'Surrogate',
        enabled: true,
        modelType: intent.surrogate.type as any,
        minTrials: intent.surrogate.min_trials,
      });
      edges.push({ id: `e_${algoId}_${surId}`, source: algoId, target: surId });
    }

    set({
      nodes,
      edges,
      selectedNode: null,
      validation: { valid: false, errors: [], warnings: [] },
    });
  },

  loadFromConfig: (config) => {
    // Convert optimization_config.json format to intent format, then load
    const intent: OptimizationIntent = {
      version: '1.0',
      source: 'canvas',
      timestamp: new Date().toISOString(),
      model: {
        path: config.model?.path,
        type: config.model?.type,
      },
      solver: {
        type: config.solver?.solution ? `SOL${config.solver.solution}` : undefined,
      },
      design_variables: (config.design_variables || []).map(dv => ({
        name: dv.expression_name || dv.name,
        min: dv.lower,
        max: dv.upper,
      })),
      extractors: [], // Will be inferred from objectives
      objectives: (config.objectives || []).map(obj => ({
        name: obj.name,
        direction: (obj.direction as 'minimize' | 'maximize') || 'minimize',
        weight: obj.weight || 1,
        extractor: obj.extractor || '',
      })),
      constraints: (config.constraints || []).map(con => ({
        name: con.name,
        operator: con.type === 'upper' ? '<=' : '>=',
        value: con.value || 0,
        extractor: con.extractor || '',
      })),
      optimization: {
        method: config.method,
        max_trials: config.max_trials,
      },
      surrogate: config.surrogate ? {
        enabled: true,
        type: config.surrogate.type,
        min_trials: config.surrogate.min_trials,
      } : undefined,
    };

    // Infer extractors from objectives and constraints
    const extractorIds = new Set<string>();
    for (const obj of intent.objectives) {
      if (obj.extractor) extractorIds.add(obj.extractor);
    }
    for (const con of intent.constraints) {
      if (con.extractor) extractorIds.add(con.extractor);
    }

    const extractorNames: Record<string, string> = {
      'E1': 'Displacement',
      'E2': 'Frequency',
      'E3': 'Solid Stress',
      'E4': 'BDF Mass',
      'E5': 'CAD Mass',
      'E8': 'Zernike (OP2)',
      'E9': 'Zernike (CSV)',
      'E10': 'Zernike (RMS)',
    };

    intent.extractors = Array.from(extractorIds).map(id => ({
      id,
      name: extractorNames[id] || id,
    }));

    get().loadFromIntent(intent);
  },
}));