/**
 * pi-todo — Persistent todo list for Pi
 * Track tasks across sessions. Priorities, tags, done/undone.
 *
 * /todo add <text> [--pri high|med|low] [--tag <t>]
 * /todo list [--tag <t>] [--pri <p>]
 * /todo done <id>
 * /todo rm <id>
 * /todo clear
 */
import type { ExtensionAPI } from '@anthropic-ai/claude-code'
import { readFileSync, writeFileSync, mkdirSync } from 'fs'
import { join } from 'path'
import { homedir } from 'os'

interface Todo { id: number; text: string; done: boolean; pri: string; tag: string; created: number }
const FILE = join(homedir(), '.pi', 'todos.json')
let nextId = 1

function load(): Todo[] {
  try { const d = JSON.parse(readFileSync(FILE,'utf-8')); nextId = Math.max(...d.map((t:Todo)=>t.id),0)+1; return d } catch { return [] }
}
function save(todos: Todo[]) { mkdirSync(join(homedir(),'.pi'),{recursive:true}); writeFileSync(FILE, JSON.stringify(todos,null,2)) }

function fmt(todos: Todo[]): string {
  if (!todos.length) return 'No todos. Use `/todo add <text>` to create one.'
  const priIcon: Record<string,string> = { high:'🔴', med:'🟡', low:'🟢' }
  const lines = todos.map(t => {
    const check = t.done ? '✅' : '⬜'
    const p = priIcon[t.pri] || '⚪'
    const tag = t.tag ? ` \`#${t.tag}\`` : ''
    return `${check} **${t.id}** ${p} ${t.text}${tag}`
  })
  const done = todos.filter(t=>t.done).length
  return `## Todos (${done}/${todos.length} done)\n\n${lines.join('\n')}`
}

export default function init(pi: ExtensionAPI) {
  pi.addCommand({ name: 'todo', description: 'Persistent todo list',
    handler: async (args) => {
      const todos = load()
      const parts = args.trim().split(/\s+/)
      const sub = parts[0]?.toLowerCase()

      if (!sub || sub === 'list') {
        let filtered = todos
        const tagIdx = parts.indexOf('--tag'); if (tagIdx>=0 && parts[tagIdx+1]) filtered = filtered.filter(t=>t.tag===parts[tagIdx+1])
        const priIdx = parts.indexOf('--pri'); if (priIdx>=0 && parts[priIdx+1]) filtered = filtered.filter(t=>t.pri===parts[priIdx+1])
        pi.sendMessage({content:fmt(filtered),display:true},{triggerTurn:false}); return
      }
      if (sub === 'add') {
        let text = args.replace(/^add\s+/,''), pri='med', tag=''
        const pm = text.match(/--pri\s+(\S+)/); if(pm){pri=pm[1];text=text.replace(/--pri\s+\S+/,'')}
        const tm = text.match(/--tag\s+(\S+)/); if(tm){tag=tm[1];text=text.replace(/--tag\s+\S+/,'')}
        text = text.trim()
        if(!text){pi.sendMessage({content:'Usage: /todo add <text>',display:true},{triggerTurn:false});return}
        todos.push({id:nextId++,text,done:false,pri,tag,created:Date.now()})
        save(todos)
        pi.sendMessage({content:`Added #${nextId-1}: ${text}`,display:true},{triggerTurn:false}); return
      }
      if (sub === 'done') {
        const id=parseInt(parts[1],10); const t=todos.find(x=>x.id===id)
        if(!t){pi.sendMessage({content:'Not found.',display:true},{triggerTurn:false});return}
        t.done=true; save(todos)
        pi.sendMessage({content:`✅ Done: ${t.text}`,display:true},{triggerTurn:false}); return
      }
      if (sub === 'rm'||sub === 'remove') {
        const id=parseInt(parts[1],10); const idx=todos.findIndex(x=>x.id===id)
        if(idx<0){pi.sendMessage({content:'Not found.',display:true},{triggerTurn:false});return}
        const removed=todos.splice(idx,1)[0]; save(todos)
        pi.sendMessage({content:`Removed: ${removed.text}`,display:true},{triggerTurn:false}); return
      }
      if (sub === 'clear') { save([]); pi.sendMessage({content:'Cleared.',display:true},{triggerTurn:false}); return }
      pi.sendMessage({content:'**/todo** add|list|done|rm|clear',display:true},{triggerTurn:false})
    }
  })
  pi.addTool({ name:'todo_add', description:'Add a persistent todo item.',
    parameters:{type:'object',properties:{text:{type:'string'},priority:{type:'string',enum:['high','med','low']},tag:{type:'string'}},required:['text']},
    handler:async(p:any)=>{const todos=load();todos.push({id:nextId++,text:p.text,done:false,pri:p.priority||'med',tag:p.tag||'',created:Date.now()});save(todos);return`Added #${nextId-1}: ${p.text}`}
  })
  pi.addTool({ name:'todo_list', description:'List all todos.',
    parameters:{type:'object',properties:{}},
    handler:async()=>fmt(load())
  })
  pi.addTool({ name:'todo_done', description:'Mark a todo as done.',
    parameters:{type:'object',properties:{id:{type:'number'}},required:['id']},
    handler:async(p:{id:number})=>{const todos=load();const t=todos.find(x=>x.id===p.id);if(!t)return'Not found.';t.done=true;save(todos);return`Done: ${t.text}`}
  })
}