#!/usr/bin/env bun

import { Command } from "commander"
import { $} from "bun"
import { basename, join } from "path"
import { homedir } from "os"
import { mkdir, symlink, unlink } from "fs/promises"
import * as git from "./git.ts"
import * as vm from "./vm.ts"
import * as state from "./state.ts"
import { spinner } from "./spinner.ts"

const pkg = await Bun.file(new URL("../package.json", import.meta.url)).json()

const program = new Command()

program.name("sandlot").description("Branch-based development with git worktrees and Apple Container").version(pkg.version)

// ── save helper ─────────────────────────────────────────────────────

/** Stage all changes, generate a commit message, and commit. Returns true on success. */
async function saveChanges(worktree: string, message?: string): Promise<boolean> {
  const spin = spinner("Staging changes")

  await $`git -C ${worktree} add .`.nothrow().quiet()

  const check = await $`git -C ${worktree} diff --staged --quiet`.nothrow().quiet()
  if (check.exitCode === 0) {
    spin.fail("No changes to commit")
    return false
  }

  let msg: string
  if (message) {
    msg = message
  } else {
    spin.text = "Starting container"
    await vm.ensure((m) => { spin.text = m })

    spin.text = "Generating commit message"
    const diff = await $`git -C ${worktree} diff --staged`.nothrow().quiet().text()
    const tmpPath = join(homedir(), '.sandlot', '.sandlot-diff-tmp')
    await Bun.write(tmpPath, diff)

    const gen = await vm.exec(
      join(homedir(), '.sandlot'),
      'cat /sandlot/.sandlot-diff-tmp | claude -p "write a short commit message summarizing these changes. output only the message, no quotes or extra text"',
    )
    await Bun.file(tmpPath).unlink().catch(() => {})

    if (gen.exitCode !== 0) {
      spin.fail("Failed to generate commit message")
      if (gen.stderr) console.error(gen.stderr)
      return false
    }
    msg = gen.stdout
  }

  spin.text = "Committing"
  const commit = await $`git -C ${worktree} commit -m ${msg}`.nothrow().quiet()
  if (commit.exitCode !== 0) {
    spin.fail("Commit failed")
    if (commit.stderr) console.error(commit.stderr.toString().trim())
    return false
  }

  spin.succeed(`Saved: ${msg}`)
  return true
}

// ── sandlot new <branch> ──────────────────────────────────────────────

function branchFromPrompt(text: string): string {
  return text
    .toLowerCase()
    .replace(/[^a-z0-9\s-]/g, "")
    .trim()
    .split(/\s+/)
    .slice(0, 2)
    .join("-")
}

program
  .command("new")
  .argument("[branch]", "branch name or prompt (if it contains spaces)")
  .argument("[prompt]", "initial prompt for Claude")
  .option("-p, --print <prompt>", "run Claude in non-interactive mode with -p")
  .option("-n, --no-save", "skip auto-save after Claude exits")
  .description("Create a new session and launch Claude")
  .action(async (branch: string | undefined, prompt: string | undefined, opts: { print?: string; save?: boolean }) => {
    // No branch given — derive from -p prompt
    if (!branch && opts.print) {
      branch = branchFromPrompt(opts.print)
    } else if (!branch) {
      console.error("Branch name or prompt is required.")
      process.exit(1)
    } else if (branch.includes(" ")) {
      // If the "branch" contains spaces, it's actually a prompt — derive the branch name
      prompt = branch
      branch = branchFromPrompt(branch)
    }
    const root = await git.repoRoot()
    const worktreeAbs = join(homedir(), '.sandlot', basename(root), branch)

    const existing = await state.getSession(root, branch)
    if (existing) {
      console.error(`Session "${branch}" already exists. Use "sandlot open ${branch}" to re-enter it.`)
      process.exit(1)
    }

    const spin = spinner("Creating worktree")
    try {
      await git.createWorktree(branch, worktreeAbs, root)
      await mkdir(join(root, '.sandlot'), { recursive: true })
      await symlink(worktreeAbs, join(root, '.sandlot', branch))

      spin.text = "Starting container"
      await vm.ensure((msg) => { spin.text = msg })
      if (!opts.print) spin.succeed("Session ready")
    } catch (err) {
      spin.fail(String((err as Error).message ?? err))
      await git.removeWorktree(worktreeAbs, root).catch(() => {})
      await git.deleteLocalBranch(branch, root).catch(() => {})
      await unlink(join(root, '.sandlot', branch)).catch(() => {})
      process.exit(1)
    }

    const effectivePrompt = opts.print || prompt
    await state.setSession(root, {
      branch,
      worktree: worktreeAbs,
      created_at: new Date().toISOString(),
      ...(effectivePrompt ? { prompt: effectivePrompt } : {}),
    })

    if (opts.print) {
      spin.text = "Running prompt…"
      const output = await vm.claude(worktreeAbs, { prompt, print: opts.print })
      if (output) {
        spin.stop()
        process.stdout.write(output + "\n")
      } else {
        spin.succeed("Done")
      }
    } else {
      await vm.claude(worktreeAbs, { prompt, print: opts.print })
    }

    if (opts.save !== false) await saveChanges(worktreeAbs)
  })

// ── sandlot list ──────────────────────────────────────────────────────

program
  .command("list")
  .description("Show all active sessions")
  .option("--json", "Output as JSON")
  .action(async (opts: { json?: boolean }) => {
    const root = await git.repoRoot()
    const st = await state.load(root)
    const sessions = Object.values(st.sessions)

    if (opts.json) {
      console.log(JSON.stringify(sessions, null, 2))
      return
    }

    if (sessions.length === 0) {
      console.log("No active sessions.")
      return
    }

    const branchWidth = Math.max(6, ...sessions.map((s) => s.branch.length))
    const cols = process.stdout.columns || 80
    const prefixWidth = branchWidth + 2

    console.log(`${"BRANCH".padEnd(branchWidth)}  PROMPT`)
    for (const s of sessions) {
      const prompt = s.prompt ?? ""
      const maxPrompt = cols - prefixWidth
      const truncated = maxPrompt > 3 && prompt.length > maxPrompt ? prompt.slice(0, maxPrompt - 3) + "..." : prompt
      console.log(`${s.branch.padEnd(branchWidth)}  ${truncated}`)
    }
  })

// ── sandlot open <branch> ─────────────────────────────────────────────

program
  .command("open")
  .argument("<branch>", "branch name")
  .argument("[prompt]", "initial prompt for Claude")
  .option("-p, --print <prompt>", "run Claude in non-interactive mode with -p")
  .option("-n, --no-save", "skip auto-save after Claude exits")
  .description("Re-enter an existing session")
  .action(async (branch: string, prompt: string | undefined, opts: { print?: string; save?: boolean }) => {
    const root = await git.repoRoot()
    const session = await state.getSession(root, branch)

    if (!session) {
      console.error(`No session found for branch "${branch}".`)
      process.exit(1)
    }

    const effectivePrompt = opts.print || prompt
    if (effectivePrompt) {
      await state.setSession(root, { ...session, prompt: effectivePrompt })
    }

    const spin = spinner("Starting container")
    await vm.ensure((msg) => { spin.text = msg })

    if (opts.print) {
      spin.text = "Running prompt…"
      const output = await vm.claude(session.worktree, { prompt, print: opts.print })
      if (output) {
        spin.stop()
        process.stdout.write(output + "\n")
      } else {
        spin.succeed("Done")
      }
    } else {
      spin.succeed("Session ready")
      await vm.claude(session.worktree, { prompt, print: opts.print })
    }

    if (opts.save !== false) await saveChanges(session.worktree)
  })

// ── sandlot close <branch> ───────────────────────────────────────────

const closeAction = async (branch: string) => {
  const root = await git.repoRoot()
  const session = await state.getSession(root, branch)
  const worktreeAbs = session?.worktree ?? join(homedir(), '.sandlot', basename(root), branch)

  await git.removeWorktree(worktreeAbs, root)
    .catch((e) => console.warn(`Failed to remove worktree: ${e.message}`))

  await unlink(join(root, '.sandlot', branch))
    .catch(() => {}) // symlink may not exist

  await git.deleteLocalBranch(branch, root)
    .catch((e) => console.warn(`Failed to delete branch ${branch}: ${e.message}`))

  if (session) {
    await state.removeSession(root, branch)
  }

  console.log(`Closed session ${branch}`)
}

// ── sandlot merge <branch> ──────────────────────────────────────────

program
  .command("merge")
  .argument("<branch>", "branch name")
  .description("Merge a branch into main and close the session")
  .action(async (branch: string) => {
    const root = await git.repoRoot()

    const conflicts = await git.merge(branch, root)

    if (conflicts.length === 0) {
      console.log(`Merged ${branch} into current branch`)
      await closeAction(branch)
      return
    }

    // Resolve conflicts with Claude
    console.log(`Merge conflicts in ${conflicts.length} file(s). Resolving with Claude...`)
    const spin = spinner("Starting container")

    try {
      await vm.ensure((msg) => { spin.text = msg })

      for (const file of conflicts) {
        spin.text = `Resolving ${file}`
        const content = await Bun.file(join(root, file)).text()

        const tmpPath = join(homedir(), '.sandlot', '.conflict-tmp')
        await Bun.write(tmpPath, content)

        const resolved = await vm.exec(
          join(homedir(), '.sandlot'),
          'cat /sandlot/.conflict-tmp | claude -p "resolve this merge conflict. output ONLY the resolved file content with no markdown fences, no explanation, no surrounding text."',
        )

        await Bun.file(tmpPath).unlink().catch(() => {})

        if (resolved.exitCode !== 0) {
          throw new Error(`Claude failed to resolve ${file}: ${resolved.stderr}`)
        }

        await Bun.write(join(root, file), resolved.stdout + "\n")
        await git.stageFile(file, root)
      }

      await git.commitMerge(root)
      spin.succeed(`Resolved ${conflicts.length} conflict(s) and merged ${branch}`)
    } catch (err) {
      spin.fail(String((err as Error).message ?? err))
      await git.abortMerge(root)
      process.exit(1)
    }

    await closeAction(branch)
  })

program
  .command("close")
  .argument("<branch>", "branch name")
  .description("Remove a worktree and clean up the session")
  .action(closeAction)

program
  .command("rm", { hidden: true })
  .argument("<branch>", "branch name")
  .action(closeAction)

// ── sandlot save <branch> ───────────────────────────────────────────

program
  .command("save")
  .argument("<branch>", "branch name")
  .argument("[message]", "commit message (AI-generated if omitted)")
  .description("Stage all changes and commit")
  .action(async (branch: string, message?: string) => {
    const root = await git.repoRoot()
    const session = await state.getSession(root, branch)
    if (!session) {
      console.error(`No session found for branch "${branch}".`)
      process.exit(1)
    }

    const ok = await saveChanges(session.worktree, message)
    if (!ok) process.exit(1)
  })

// ── sandlot diff <branch> ───────────────────────────────────────────

program
  .command("diff")
  .argument("<branch>", "branch name")
  .description("Show uncommitted changes, or full branch diff vs main")
  .action(async (branch: string) => {
    const root = await git.repoRoot()
    const session = await state.getSession(root, branch)
    if (!session) {
      console.error(`No session found for branch "${branch}".`)
      process.exit(1)
    }

    // Check for uncommitted changes (staged + unstaged)
    const status = await $`git -C ${session.worktree} status --porcelain`.nothrow().quiet()
    if (status.exitCode !== 0) {
      console.error("git status failed")
      process.exit(1)
    }

    let diff: string
    if (status.text().trim().length > 0) {
      // Show uncommitted changes (both staged and unstaged)
      const result = await $`git -C ${session.worktree} diff --color=always HEAD`.nothrow().quiet()
      if (result.exitCode !== 0) {
        // HEAD may not exist yet (no commits); fall back to showing all tracked + untracked
        const fallback = await $`git -C ${session.worktree} diff --color=always`.nothrow().quiet()
        diff = fallback.text()
      } else {
        diff = result.text()
      }
    } else {
      // No uncommitted changes — show full branch diff vs main
      const main = await git.mainBranch(root)
      const result = await $`git -C ${session.worktree} diff --color=always ${main}...${branch}`.nothrow().quiet()
      if (result.exitCode !== 0) {
        console.error("git diff failed")
        process.exit(1)
      }
      diff = result.text()
    }

    const lines = diff.split("\n").length
    const termHeight = process.stdout.rows || 24
    if (lines > termHeight) {
      const pager = Bun.spawn(["less", "-R"], { stdin: "pipe", stdout: "inherit", stderr: "inherit" })
      pager.stdin.write(diff)
      pager.stdin.end()
      await pager.exited
    } else {
      process.stdout.write(diff)
    }
  })

// ── sandlot log <branch> ────────────────────────────────────────────

program
  .command("log")
  .argument("<branch>", "branch name")
  .description("Show commits on a branch that are not on main")
  .action(async (branch: string) => {
    const root = await git.repoRoot()
    const session = await state.getSession(root, branch)
    if (!session) {
      console.error(`No session found for branch "${branch}".`)
      process.exit(1)
    }

    const result = await $`git -C ${session.worktree} log main..HEAD`.nothrow()
    if (result.exitCode !== 0) {
      console.error("git log failed")
      process.exit(1)
    }
  })

// ── sandlot dir <branch> ────────────────────────────────────────────

program
  .command("dir")
  .argument("<branch>", "branch name")
  .description("Print the worktree path for a session")
  .action(async (branch: string) => {
    const root = await git.repoRoot()
    const session = await state.getSession(root, branch)
    if (!session) {
      console.error(`No session found for branch "${branch}".`)
      process.exit(1)
    }

    process.stdout.write(session.worktree + "\n")
  })

// ── sandlot vm ───────────────────────────────────────────────────────

const vmCmd = program.command("vm").description("Manage the sandlot VM")

vmCmd
  .command("shell")
  .description("Open a shell in the VM")
  .action(async () => {
    await vm.ensure()
    await vm.shell()
  })

vmCmd
  .command("status")
  .description("Show VM status")
  .action(async () => {
    const s = await vm.status()
    console.log(s)
  })

vmCmd
  .command("info")
  .description("Show VM system info (via neofetch)")
  .action(async () => {
    await vm.ensure()
    await vm.info()
  })

vmCmd
  .command("stop")
  .description("Stop the VM")
  .action(async () => {
    await vm.stop()
    console.log("VM stopped")
  })

vmCmd
  .command("destroy")
  .description("Stop and delete the VM")
  .action(async () => {
    await vm.destroy()
    console.log("VM destroyed")
  })

program.parseAsync().catch((err) => {
  console.error(err.message ?? err)
  process.exit(1)
})