import * as fs from "fs"
import * as path from "path"
import { getConfigDir } from "../auth/config"

export interface MemoryCategory {
  key: string
  filename: string
  description: string
}

export const MEMORY_CATEGORIES: MemoryCategory[] = [
  { key: "preferences", filename: "preferences.md", description: "User preferences (language, style, conventions)" },
  { key: "project", filename: "project-notes.md", description: "Project knowledge (architecture, patterns, key decisions)" },
  { key: "decisions", filename: "decisions.md", description: "Past decisions and rationale" },
  { key: "architecture", filename: "architecture.md", description: "System architecture notes" },
]

export function getMemoryDir(): string {
  return path.join(getConfigDir(), "memory")
}

export function ensureMemoryDir(): void {
  const dir = getMemoryDir()
  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true })
  }
  for (const cat of MEMORY_CATEGORIES) {
    const filePath = path.join(dir, cat.filename)
    if (!fs.existsSync(filePath)) {
      fs.writeFileSync(filePath, `# ${cat.description}\n\n`, "utf-8")
    }
  }
}

export function readMemory(key: string): string {
  const cat = MEMORY_CATEGORIES.find((c) => c.key === key)
  if (!cat) return ""
  const filePath = path.join(getMemoryDir(), cat.filename)
  try {
    return fs.readFileSync(filePath, "utf-8").trim()
  } catch {
    return ""
  }
}

export function writeMemory(key: string, content: string): void {
  const cat = MEMORY_CATEGORIES.find((c) => c.key === key)
  if (!cat) return
  ensureMemoryDir()
  const filePath = path.join(getMemoryDir(), cat.filename)
  fs.writeFileSync(filePath, content, "utf-8")
}

export function appendMemory(key: string, line: string): void {
  const current = readMemory(key)
  writeMemory(key, current + "\n" + line)
}

export function readAllMemory(): Record<string, string> {
  const result: Record<string, string> = {}
  for (const cat of MEMORY_CATEGORIES) {
    const content = readMemory(cat.key)
    if (content) result[cat.key] = content
  }
  return result
}

export function buildMemoryPrompt(): string {
  const memories = readAllMemory()
  const entries = Object.entries(memories)
  if (entries.length === 0) return ""
  const lines = ["## User Memory"]
  for (const [key, content] of entries) {
    const cat = MEMORY_CATEGORIES.find((c) => c.key === key)
    if (cat && content.trim()) {
      lines.push(`### ${cat.description}`)
      lines.push(content)
    }
  }
  return lines.join("\n")
}