import { describe, it, expect, beforeEach, afterEach } from 'vitest'
import fs from 'node:fs'
import path from 'node:path'
import os from 'node:os'
import { loadAgents, findAgent } from '../../src/agent/agents-store.js'

// We'll point the agents dir to a temp directory by monkey-patching os.homedir
// during tests that need a real directory. For most tests we can rely on the
// behaviour when ~/.squeezr-code/agents does NOT exist.

let tmpHome: string
let origHomedir: () => string

beforeEach(() => {
  tmpHome = fs.mkdtempSync(path.join(os.tmpdir(), 'sq-agents-test-'))
  origHomedir = os.homedir
  // Override homedir so agents-store reads our tmpHome
  ;(os as { homedir: () => string }).homedir = () => tmpHome
})

afterEach(() => {
  ;(os as { homedir: () => string }).homedir = origHomedir
  fs.rmSync(tmpHome, { recursive: true, force: true })
})

function agentsDir(): string {
  return path.join(tmpHome, '.squeezr-code', 'agents')
}

function writeAgent(name: string, content: string): void {
  fs.mkdirSync(agentsDir(), { recursive: true })
  fs.writeFileSync(path.join(agentsDir(), `${name}.md`), content, 'utf-8')
}

describe('loadAgents', () => {
  it('returns empty array when agents dir does not exist', () => {
    expect(loadAgents()).toEqual([])
  })

  it('returns empty array when agents dir is empty', () => {
    fs.mkdirSync(agentsDir(), { recursive: true })
    expect(loadAgents()).toEqual([])
  })

  it('ignores non-.md files', () => {
    fs.mkdirSync(agentsDir(), { recursive: true })
    fs.writeFileSync(path.join(agentsDir(), 'readme.txt'), 'ignore me')
    expect(loadAgents()).toHaveLength(0)
  })

  it('parses a simple agent without frontmatter', () => {
    writeAgent('simple', 'You are a helpful assistant.')
    const agents = loadAgents()
    expect(agents).toHaveLength(1)
    expect(agents[0].name).toBe('simple')
    expect(agents[0].systemPrompt).toContain('You are a helpful assistant.')
    // description defaults to first line
    expect(agents[0].description).toBe('You are a helpful assistant.')
  })

  it('parses an agent with full frontmatter', () => {
    const content = `---
description: Security-focused code reviewer
tools: Read, Grep, Glob
model: opus
---
You are a security-focused code reviewer.
Look for SQL injection and XSS vulnerabilities.`
    writeAgent('security-reviewer', content)
    const agents = loadAgents()
    expect(agents).toHaveLength(1)
    const spec = agents[0]
    expect(spec.name).toBe('security-reviewer')
    expect(spec.description).toBe('Security-focused code reviewer')
    expect(spec.tools).toEqual(['Read', 'Grep', 'Glob'])
    expect(spec.model).toBe('opus')
    expect(spec.systemPrompt).toContain('You are a security-focused code reviewer.')
    expect(spec.systemPrompt).not.toContain('---')
  })

  it('parses multiple agents', () => {
    writeAgent('agent-a', '---\ndescription: Agent A\n---\nDo A things.')
    writeAgent('agent-b', '---\ndescription: Agent B\n---\nDo B things.')
    const agents = loadAgents()
    expect(agents).toHaveLength(2)
    const names = agents.map(a => a.name).sort()
    expect(names).toEqual(['agent-a', 'agent-b'])
  })

  it('description truncates to 80 chars when no frontmatter', () => {
    const longLine = 'A'.repeat(100)
    writeAgent('long-desc', longLine)
    const agents = loadAgents()
    expect(agents[0].description).toHaveLength(80)
  })

  it('tools is undefined when not in frontmatter', () => {
    writeAgent('no-tools', '---\ndescription: No tools\n---\nSystem prompt.')
    const agents = loadAgents()
    expect(agents[0].tools).toBeUndefined()
  })

  it('model is undefined when not in frontmatter', () => {
    writeAgent('no-model', '---\ndescription: No model\n---\nSystem prompt.')
    const agents = loadAgents()
    expect(agents[0].model).toBeUndefined()
  })
})

describe('findAgent', () => {
  it('returns null when agent does not exist', () => {
    expect(findAgent('nonexistent')).toBeNull()
  })

  it('returns null when agents dir does not exist', () => {
    expect(findAgent('anything')).toBeNull()
  })

  it('finds an existing agent by name', () => {
    writeAgent('my-agent', '---\ndescription: My agent\n---\nDo things.')
    const spec = findAgent('my-agent')
    expect(spec).not.toBeNull()
    expect(spec?.name).toBe('my-agent')
    expect(spec?.description).toBe('My agent')
  })

  it('returns null for a different name', () => {
    writeAgent('my-agent', '---\ndescription: My agent\n---\nDo things.')
    expect(findAgent('other-agent')).toBeNull()
  })
})