import React, { useState, useEffect } from 'react';
import { Play, Plus, Trash2, Save, Rocket, Clock, FileText } from 'lucide-react';
import { Workflow, WorkflowStep, Note } from '../types';
import { STORAGE_KEYS, DEFAULT_WORKFLOWS } from '../constants';

interface WorkflowPanelProps {
    templates: Note[];
    onStartWorkflow: (workflow: Workflow) => void;
}

export const WorkflowPanel: React.FC<WorkflowPanelProps> = ({ templates, onStartWorkflow }) => {
    const [workflows, setWorkflows] = useState<Workflow[]>(() => {
        const stored = localStorage.getItem(STORAGE_KEYS.WORKFLOWS);
        return stored ? JSON.parse(stored) : DEFAULT_WORKFLOWS;
    });

    const [isEditing, setIsEditing] = useState(false);
    const [editingWorkflow, setEditingWorkflow] = useState<Workflow | null>(null);

    useEffect(() => {
        localStorage.setItem(STORAGE_KEYS.WORKFLOWS, JSON.stringify(workflows));
    }, [workflows]);

    const handleCreateNew = () => {
        setEditingWorkflow({
            id: `workflow-${Date.now()}`,
            name: 'New Workflow',
            description: '',
            steps: [{ templateId: '', delayMinutes: 0 }]
        });
        setIsEditing(true);
    };

    const handleSave = () => {
        if (!editingWorkflow) return;
        if (!editingWorkflow.name.trim()) {
            alert('Workflow name is required.');
            return;
        }

        if (editingWorkflow.steps.some(s => !s.templateId)) {
            alert('All steps must have a selected template.');
            return;
        }

        setWorkflows(prev => {
            const existingIndex = prev.findIndex(w => w.id === editingWorkflow.id);
            if (existingIndex >= 0) {
                const newWorkflows = [...prev];
                newWorkflows[existingIndex] = editingWorkflow;
                return newWorkflows;
            }
            return [...prev, editingWorkflow];
        });

        setIsEditing(false);
        setEditingWorkflow(null);
    };

    const handleDelete = (id: string) => {
        if (confirm('Delete this workflow?')) {
            setWorkflows(prev => prev.filter(w => w.id !== id));
        }
    };

    const addStep = () => {
        if (editingWorkflow) {
            setEditingWorkflow({
                ...editingWorkflow,
                steps: [...editingWorkflow.steps, { templateId: '', delayMinutes: 30 }]
            });
        }
    };

    const removeStep = (index: number) => {
        if (editingWorkflow && editingWorkflow.steps.length > 1) {
            const newSteps = [...editingWorkflow.steps];
            newSteps.splice(index, 1);
            setEditingWorkflow({ ...editingWorkflow, steps: newSteps });
        }
    };

    const updateStep = (index: number, field: keyof WorkflowStep, value: string | number) => {
        if (editingWorkflow) {
            const newSteps = [...editingWorkflow.steps];
            newSteps[index] = { ...newSteps[index], [field]: value };
            setEditingWorkflow({ ...editingWorkflow, steps: newSteps });
        }
    };

    return (
        <div className="flex flex-col h-full bg-white p-6 overflow-y-auto">
            <div className="max-w-3xl mx-auto w-full space-y-6">
                <div className="flex justify-between items-center">
                    <div>
                        <h2 className="text-2xl font-bold flex items-center gap-2 text-gray-900">
                            <Rocket className="w-6 h-6 text-indigo-600" />
                            Workflow Builder
                        </h2>
                        <p className="text-gray-500 mt-1 text-sm">Create sequences of templates that fire on a timer.</p>
                    </div>
                    {!isEditing && (
                        <button
                            onClick={handleCreateNew}
                            className="bg-indigo-600 hover:bg-indigo-700 text-white px-4 py-2 rounded-xl text-sm font-bold flex items-center gap-2 transition-all"
                        >
                            <Plus className="w-4 h-4" /> New Workflow
                        </button>
                    )}
                </div>

                {isEditing && editingWorkflow ? (
                    <div className="bg-gray-50 border border-gray-200 rounded-2xl p-6 space-y-6 animate-in fade-in slide-in-from-top-4">
                        <div className="flex justify-between items-center border-b border-gray-200 pb-4">
                            <h3 className="text-lg font-bold text-gray-800">Edit Workflow</h3>
                            <div className="flex gap-2">
                                <button
                                    onClick={() => { setIsEditing(false); setEditingWorkflow(null); }}
                                    className="px-4 py-2 text-gray-500 hover:bg-gray-200 rounded-xl text-sm font-bold transition-all"
                                >
                                    Cancel
                                </button>
                                <button
                                    onClick={handleSave}
                                    className="bg-indigo-600 hover:bg-indigo-700 text-white px-4 py-2 rounded-xl text-sm font-bold flex items-center gap-2 transition-all shadow-sm"
                                >
                                    <Save className="w-4 h-4" /> Save Workflow
                                </button>
                            </div>
                        </div>

                        <div className="space-y-4">
                            <div>
                                <label className="block text-xs font-bold text-gray-600 uppercase tracking-wider mb-1">Workflow Name</label>
                                <input
                                    type="text"
                                    value={editingWorkflow.name}
                                    onChange={(e) => setEditingWorkflow({ ...editingWorkflow, name: e.target.value })}
                                    className="w-full px-4 py-2 border border-gray-200 rounded-xl focus:ring-2 focus:ring-indigo-500 outline-none transition-all"
                                    placeholder="e.g. Code Review & Deploy"
                                />
                            </div>
                            <div>
                                <label className="block text-xs font-bold text-gray-600 uppercase tracking-wider mb-1">Description (Optional)</label>
                                <input
                                    type="text"
                                    value={editingWorkflow.description}
                                    onChange={(e) => setEditingWorkflow({ ...editingWorkflow, description: e.target.value })}
                                    className="w-full px-4 py-2 border border-gray-200 rounded-xl focus:ring-2 focus:ring-indigo-500 outline-none transition-all text-sm"
                                    placeholder="What does this sequence do?"
                                />
                            </div>

                            <div className="pt-4 border-t border-gray-200">
                                <div className="flex justify-between items-center mb-4">
                                    <label className="text-xs font-bold text-gray-800 uppercase tracking-wider">Execution Steps</label>
                                </div>
                                <div className="space-y-4">
                                    {editingWorkflow.steps.map((step, idx) => (
                                        <div key={idx} className="flex gap-3 bg-white p-4 rounded-xl border border-gray-200 shadow-sm relative">
                                            <div className="flex flex-col items-center justify-center bg-indigo-50 text-indigo-700 font-bold rounded-lg w-8 h-8 flex-shrink-0">
                                                {idx + 1}
                                            </div>
                                            <div className="flex-1 grid grid-cols-1 md:grid-cols-2 gap-4">
                                                <div>
                                                    <label className="block text-[10px] font-bold text-gray-500 uppercase tracking-wider mb-1 flex items-center gap-1">
                                                        <FileText className="w-3 h-3" /> Select Template
                                                    </label>
                                                    <select
                                                        value={step.templateId}
                                                        onChange={(e) => updateStep(idx, 'templateId', e.target.value)}
                                                        className="w-full px-3 py-2 border border-gray-200 rounded-lg text-sm outline-none focus:ring-2 focus:ring-indigo-500 bg-white"
                                                    >
                                                        <option value="">-- Choose Template --</option>
                                                        {templates.map(t => (
                                                            <option key={t.id} value={t.id}>{t.title || t.id}</option>
                                                        ))}
                                                    </select>
                                                </div>
                                                <div>
                                                    <label className="block text-[10px] font-bold text-gray-500 uppercase tracking-wider mb-1 flex items-center gap-1">
                                                        <Clock className="w-3 h-3" /> Delay Before Firing (Mins)
                                                    </label>
                                                    <input
                                                        type="number"
                                                        min="0"
                                                        value={step.delayMinutes}
                                                        onChange={(e) => updateStep(idx, 'delayMinutes', parseInt(e.target.value) || 0)}
                                                        disabled={idx === 0}
                                                        className="w-full px-3 py-2 border border-gray-200 rounded-lg text-sm outline-none focus:ring-2 focus:ring-indigo-500 disabled:bg-gray-100 disabled:text-gray-400"
                                                    />
                                                </div>
                                            </div>
                                            {idx > 0 && (
                                                <button
                                                    onClick={() => removeStep(idx)}
                                                    className="p-2 text-gray-400 hover:text-red-500 hover:bg-red-50 rounded-lg transition-all absolute right-2 top-2"
                                                >
                                                    <Trash2 className="w-4 h-4" />
                                                </button>
                                            )}
                                        </div>
                                    ))}
                                </div>
                                <button
                                    onClick={addStep}
                                    className="mt-4 flex items-center gap-1 text-sm font-bold text-indigo-600 hover:text-indigo-700 bg-indigo-50 hover:bg-indigo-100 px-3 py-2 rounded-lg transition-colors"
                                >
                                    <Plus className="w-4 h-4" /> Add Step
                                </button>
                            </div>
                        </div>
                    </div>
                ) : (
                    <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                        {workflows.map(wf => (
                            <div key={wf.id} className="bg-white border border-gray-200 rounded-2xl p-5 hover:border-indigo-300 transition-all shadow-sm hover:shadow-md flex flex-col group relative">
                                {wf.id !== 'hf-deployment-cue' && (
                                    <button
                                        onClick={() => handleDelete(wf.id)}
                                        className="absolute top-4 right-4 p-2 text-gray-400 hover:text-red-500 bg-gray-50 hover:bg-red-50 rounded-lg transition-all opacity-0 group-hover:opacity-100"
                                    >
                                        <Trash2 className="w-4 h-4" />
                                    </button>
                                )}

                                <div className="flex-1">
                                    <h3 className="text-lg font-bold text-gray-900 mb-1 flex items-center gap-2">
                                        {wf.name}
                                        {wf.id === 'hf-deployment-cue' && <span className="bg-indigo-100 text-indigo-700 text-[10px] px-2 py-0.5 rounded-full uppercase tracking-wider">System</span>}
                                    </h3>
                                    <p className="text-sm text-gray-500 mb-4">{wf.description || 'No description provided.'}</p>

                                    <div className="space-y-2 mb-6">
                                        <div className="text-xs font-bold text-gray-400 uppercase tracking-wider border-b border-gray-100 pb-1 mb-2">Sequence</div>
                                        {wf.steps.map((step, idx) => (
                                            <div key={idx} className="flex items-center text-xs text-gray-600">
                                                <span className="w-5 font-bold text-gray-400">{idx + 1}.</span>
                                                <span className="font-medium truncate flex-1">{templates.find(t => t.id === step.templateId)?.title || step.templateId}</span>
                                                {step.delayMinutes > 0 && (
                                                    <span className="text-indigo-500 flex items-center gap-1 font-bold bg-indigo-50 px-1.5 py-0.5 rounded ml-2 whitespace-nowrap">
                                                        <Clock className="w-3 h-3" /> +{step.delayMinutes}m
                                                    </span>
                                                )}
                                            </div>
                                        ))}
                                    </div>
                                </div>

                                <div className="flex gap-2">
                                    <button
                                        onClick={() => onStartWorkflow(wf)}
                                        className="flex-1 bg-indigo-50 hover:bg-indigo-600 text-indigo-700 hover:text-white py-2.5 rounded-xl text-sm font-bold flex items-center justify-center gap-2 transition-all shadow-sm group/btn"
                                    >
                                        <Play className="w-4 h-4 fill-current opacity-70 group-hover/btn:opacity-100" /> Start Workflow
                                    </button>
                                    <button
                                        onClick={() => {
                                            setEditingWorkflow(wf);
                                            setIsEditing(true);
                                        }}
                                        className="px-4 py-2.5 bg-white border border-gray-200 hover:bg-gray-50 text-gray-600 rounded-xl text-sm font-bold transition-colors"
                                    >
                                        Edit
                                    </button>
                                </div>
                            </div>
                        ))}
                        {workflows.length === 0 && (
                            <div className="col-span-full py-12 flex flex-col items-center justify-center text-gray-400 border-2 border-dashed border-gray-200 rounded-2xl">
                                <Rocket className="w-12 h-12 mb-3 text-gray-300" />
                                <p>No workflows created yet.</p>
                            </div>
                        )}
                    </div>
                )}
            </div>
        </div>
    );
};