/**
 * public/projects.ts — Projects panel for the home screen (v0.6).
 *
 * Renders a grid of discovered git repositories fetched from GET /projects.
 * Each card shows: repo name, branch chip, dirty indicator, last-active time,
 * and running sessions (1:N). Supports live search and per-project favourites
 * persisted to localStorage.
 *
 * Pure helpers (filterProjects, sortProjects, getFavs, saveFavs, toggleFav)
 * are exported for unit testing without DOM. mountProjects is the thin wiring.
 *
 * Timer lifecycle mirrors launcher.ts: auto-refresh every 5 s while visible,
 * stopped + cleaned up on hide.
 */

import type {
  ProjectInfo,
  ProjectSessionRef,
  ClaudeStatus,
  ProjectDetail,
  WorktreeInfo,
} from '../src/types.js'
import { el, relTime, statusText } from './preview-grid.js'
import { CLAUDE_LOGO, CODEX_LOGO, VSCODE_LOGO } from './icons.js'

/* ── Constants ───────────────────────────────────────────────────────────── */

const FAV_KEY = 'web-terminal:proj-favs'
const REFRESH_MS = 5000

/* ── Public contract (consumed by P6 — tabs.ts wiring) ──────────────────── */

export interface ProjectsHooks {
  /** Spawn a new terminal session in the repo running `cmd` (default: claude). */
  onOpenProject: (repoPath: string, repoName: string, cmd?: string) => void
  /** Enter an already-running session by id. */
  onEnterSession: (id: string) => void
}

export interface ProjectsPanel {
  setVisible(v: boolean): void
  refresh(): void
}

/* ── Pure helpers (exported for unit tests) ──────────────────────────────── */

/**
 * Filter projects by name or path substring (case-insensitive).
 * Returns a new array; never mutates the input.
 */
export function filterProjects(projects: readonly ProjectInfo[], query: string): ProjectInfo[] {
  const trimmed = query.trim()
  if (!trimmed) return [...projects]
  const lower = trimmed.toLowerCase()
  return projects.filter(
    (p) => p.name.toLowerCase().includes(lower) || p.path.toLowerCase().includes(lower),
  )
}

/**
 * Sort projects: favourites first, then by lastActiveMs descending.
 * Returns a new array; never mutates the input.
 */
export function sortProjects(
  projects: readonly ProjectInfo[],
  favs: ReadonlySet<string>,
): ProjectInfo[] {
  return [...projects].sort((a, b) => {
    const aFav = favs.has(a.path) ? 0 : 1
    const bFav = favs.has(b.path) ? 0 : 1
    if (aFav !== bFav) return aFav - bFav
    return (b.lastActiveMs ?? 0) - (a.lastActiveMs ?? 0)
  })
}

/** Load persisted favourite project paths from localStorage. */
export function getFavs(): Set<string> {
  try {
    const raw = localStorage.getItem(FAV_KEY)
    if (!raw) return new Set()
    const parsed: unknown = JSON.parse(raw)
    // Never trust persisted data: keep only string entries (corrupt/tampered
    // localStorage could otherwise poison the Set<string> used for path matching).
    if (!Array.isArray(parsed)) return new Set()
    return new Set(parsed.filter((x): x is string => typeof x === 'string'))
  } catch {
    return new Set()
  }
}

/** Persist a set of favourite project paths to localStorage. */
export function saveFavs(favs: ReadonlySet<string>): void {
  try {
    localStorage.setItem(FAV_KEY, JSON.stringify([...favs]))
  } catch {
    // localStorage unavailable — run without persistence
  }
}

/**
 * Immutable toggle: add if absent, remove if present.
 * Returns a new Set; never mutates the original.
 */
export function toggleFav(favs: ReadonlySet<string>, path: string): Set<string> {
  const next = new Set(favs)
  if (next.has(path)) {
    next.delete(path)
  } else {
    next.add(path)
  }
  return next
}

/* ── Fetch ───────────────────────────────────────────────────────────────── */

/** Coerce one untrusted /projects element into a safe ProjectInfo, or null.
 *  Guarantees `sessions` is always an array so card rendering never throws on a
 *  malformed response (never trust external data — API responses included). */
export function normalizeProject(p: unknown): ProjectInfo | null {
  if (p === null || typeof p !== 'object') return null
  const o = p as Record<string, unknown>
  if (typeof o['name'] !== 'string' || typeof o['path'] !== 'string') return null
  const sessions = Array.isArray(o['sessions']) ? (o['sessions'] as ProjectSessionRef[]) : []
  return {
    name: o['name'],
    path: o['path'],
    isGit: o['isGit'] === true,
    ...(typeof o['branch'] === 'string' ? { branch: o['branch'] } : {}),
    ...(typeof o['dirty'] === 'boolean' ? { dirty: o['dirty'] } : {}),
    ...(typeof o['lastActiveMs'] === 'number' ? { lastActiveMs: o['lastActiveMs'] } : {}),
    sessions,
  }
}

async function fetchProjects(): Promise<ProjectInfo[]> {
  try {
    const res = await fetch('/projects')
    const data: unknown = await res.json()
    if (!Array.isArray(data)) return []
    return data.map(normalizeProject).filter((x): x is ProjectInfo => x !== null)
  } catch {
    return []
  }
}

/** Fetch one project's detail (branch/worktrees + sessions). null on any error. */
async function fetchProjectDetail(projectPath: string): Promise<ProjectDetail | null> {
  try {
    const res = await fetch(`/projects/detail?path=${encodeURIComponent(projectPath)}`)
    if (!res.ok) return null
    return (await res.json()) as ProjectDetail
  } catch {
    return null
  }
}

/** Kill a running session (manage-page DELETE; same-origin → Origin guard passes). */
async function killSession(id: string): Promise<void> {
  try {
    await fetch(`/live-sessions/${encodeURIComponent(id)}`, { method: 'DELETE' })
  } catch {
    // best-effort — the refresh that follows will reflect the real state
  }
}

/* ── Status helpers ──────────────────────────────────────────────────────── */

function sessionDotClass(status: ClaudeStatus): string {
  return `proj-session-dot proj-dot-${status}`
}

/* ── Card sub-elements ───────────────────────────────────────────────────── */

function makeSessionRow(
  sess: { id: string; title?: string; status: ClaudeStatus; clientCount: number },
  onEnterSession: (id: string) => void,
): HTMLElement {
  const row = el('div', 'proj-session-row')
  row.setAttribute('role', 'button')
  row.tabIndex = 0

  const dot = el('span', sessionDotClass(sess.status))
  const title = el('span', 'proj-session-title', sess.title ?? 'claude')
  const badge = el('span', 'proj-session-badge', `👁 ${sess.clientCount}`)

  row.append(dot, title, badge)

  row.addEventListener('click', () => onEnterSession(sess.id))
  row.addEventListener('keydown', (e) => {
    if (e.key === 'Enter' || e.key === ' ') {
      e.preventDefault()
      onEnterSession(sess.id)
    }
  })

  return row
}

/** Ask the host to open this project in the editor (POST /open-in-editor → `code <path>`). */
async function openProjectInEditor(repoPath: string): Promise<void> {
  try {
    const res = await fetch('/open-in-editor', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ path: repoPath }),
    })
    if (!res.ok) console.error('[projects] open in editor failed:', res.status)
  } catch (err) {
    console.error('[projects] open in editor error:', err)
  }
}

interface LauncherOpts {
  /** Highlight the button (a matching session is running). */
  active?: boolean
  /** Optional count badge (only shown when > 1). */
  count?: number
}

/** One launcher button: brand logo (currentColor) + caption; colour set via CSS. */
function makeLauncher(
  logo: string,
  label: string,
  cls: string,
  title: string,
  onClick: () => void,
  opts?: LauncherOpts,
): HTMLElement {
  const active = opts?.active === true
  const btn = el('button', `proj-launch ${cls}${active ? ' proj-launch-active' : ''}`)
  btn.title = title
  btn.setAttribute('aria-label', title)
  btn.innerHTML = logo // static, trusted brand SVG — no user data
  btn.append(el('span', 'proj-launch-cap', label))
  if (active && opts?.count !== undefined && opts.count > 1) {
    btn.append(el('span', 'proj-launch-badge', String(opts.count)))
  }
  btn.addEventListener('click', (e) => {
    e.stopPropagation()
    onClick()
  })
  return btn
}

/** Count running Claude sessions in a project. A session counts as "Claude" once
 *  Claude Code hooks report a status (working/waiting/idle); plain shells and
 *  codex sessions stay 'unknown'. Used to highlight the Claude launcher. */
function activeClaudeCount(project: ProjectInfo): number {
  return project.sessions.filter((s) => !s.exited && s.status !== 'unknown').length
}

/** Launcher row for a card: Claude · Codex (new terminal sessions) · VS Code (host editor). */
function makeLauncherRow(project: ProjectInfo, hooks: ProjectsHooks): HTMLElement {
  const claude = activeClaudeCount(project)
  const claudeTitle =
    claude > 0
      ? `${claude} active Claude session${claude > 1 ? 's' : ''} in ${project.name} — start another`
      : `Start Claude in ${project.name}`

  const row = el('div', 'proj-launchers')
  row.append(
    makeLauncher(
      CLAUDE_LOGO,
      'Claude',
      'proj-launch-claude',
      claudeTitle,
      () => hooks.onOpenProject(project.path, project.name, 'claude\r'),
      { active: claude > 0, count: claude },
    ),
    makeLauncher(CODEX_LOGO, 'Codex', 'proj-launch-codex', `Start Codex in ${project.name}`, () =>
      hooks.onOpenProject(project.path, project.name, 'codex\r'),
    ),
    makeLauncher(VSCODE_LOGO, 'Code', 'proj-launch-vscode', `Open ${project.name} in VS Code`, () =>
      void openProjectInEditor(project.path),
    ),
  )
  return row
}

export function makeProjectCard(
  project: ProjectInfo,
  favs: ReadonlySet<string>,
  hooks: ProjectsHooks,
  onToggleFav: (path: string) => void,
  onOpenDetail?: (path: string) => void,
): HTMLElement {
  const card = el('div', 'proj-card')

  // ── Header ────────────────────────────────────────────────────────────────
  const header = el('div', 'proj-card-head')

  const isFav = favs.has(project.path)
  const favBtn = el('button', isFav ? 'proj-fav on' : 'proj-fav')
  favBtn.textContent = '★'
  favBtn.title = isFav ? 'Remove from favourites' : 'Add to favourites'
  favBtn.addEventListener('click', (e) => {
    e.stopPropagation()
    onToggleFav(project.path)
  })

  const name = el('span', 'proj-name', project.name)
  if (onOpenDetail) {
    name.classList.add('proj-name-link')
    name.setAttribute('role', 'button')
    name.tabIndex = 0
    name.title = `View ${project.name} details`
    name.addEventListener('click', () => onOpenDetail(project.path))
    name.addEventListener('keydown', (e) => {
      if (e.key === 'Enter' || e.key === ' ') {
        e.preventDefault()
        onOpenDetail(project.path)
      }
    })
  }

  header.append(favBtn, name)

  if (project.branch) {
    const branch = el('span', 'proj-branch', project.branch)
    header.append(branch)
  }

  if (project.dirty === true) {
    const dirty = el('span', 'proj-dirty', '●')
    dirty.title = 'Uncommitted changes'
    header.append(dirty)
  }

  card.append(header)

  // ── Meta line ─────────────────────────────────────────────────────────────
  if (project.lastActiveMs !== undefined) {
    const meta = el('div', 'proj-meta', `active ${relTime(project.lastActiveMs)} ago`)
    card.append(meta)
  }

  // ── Sessions area (1:N) — list any running sessions above the launchers ─────
  const runningSessions = project.sessions.filter((s) => !s.exited)
  if (runningSessions.length > 0) {
    const sessionsList = el('div', 'proj-sessions-list')
    for (const sess of runningSessions) {
      sessionsList.append(makeSessionRow(sess, hooks.onEnterSession))
    }
    card.append(sessionsList)
  }

  // ── Launchers (Claude · Codex · VS Code) — always available ─────────────────
  card.append(makeLauncherRow(project, hooks))

  return card
}

/* ── Detail view (branch / worktrees + active sessions) ─────────────────────── */

/** One worktree row: branch (or detached@head) + main/current/locked tags + path. */
function makeWorktreeRow(wt: WorktreeInfo): HTMLElement {
  const row = el('div', 'proj-wt-row')
  const label = wt.branch ?? (wt.head ? `detached @ ${wt.head}` : 'detached')
  row.append(el('span', 'proj-wt-branch', label))
  if (wt.isMain) row.append(el('span', 'proj-wt-tag', 'main'))
  if (wt.isCurrent) row.append(el('span', 'proj-wt-tag proj-wt-tag-current', 'current'))
  if (wt.locked) row.append(el('span', 'proj-wt-tag', 'locked'))
  if (wt.prunable) row.append(el('span', 'proj-wt-tag', 'prunable'))
  row.append(el('span', 'proj-wt-path', wt.path))
  return row
}

/** One detailed session row: status + title + metadata + Open / Kill actions. */
function makeDetailSessionRow(
  s: ProjectSessionRef,
  onEnter: (id: string) => void,
  onKill: (id: string) => void,
): HTMLElement {
  const row = el('div', 'proj-dsession')
  const dot = el('span', sessionDotClass(s.status))
  const main = el('div', 'proj-dsession-main')
  main.append(el('span', 'proj-dsession-title', s.title ?? 'session'))
  const parts: string[] = []
  if (s.status !== 'unknown') parts.push(statusText(s.status))
  parts.push(`👁 ${s.clientCount}`)
  parts.push(`started ${relTime(s.createdAt)} ago`)
  main.append(el('span', 'proj-dsession-meta', parts.join(' · ')))
  const open = el('button', 'proj-dsession-open', 'Open')
  open.addEventListener('click', () => onEnter(s.id))
  const kill = el('button', 'proj-dsession-kill', '✕')
  kill.title = 'Kill this session'
  kill.setAttribute('aria-label', 'Kill session')
  kill.addEventListener('click', () => onKill(s.id))
  row.append(dot, main, open, kill)
  return row
}

interface DetailCallbacks {
  onBack: () => void
  onKill: (id: string) => void
}

/** Render the project detail view (exported for unit tests). */
export function renderProjectDetail(
  detail: ProjectDetail | null,
  hooks: ProjectsHooks,
  cb: DetailCallbacks,
): HTMLElement {
  const root = el('div', 'proj-detail-inner')

  const back = el('button', 'proj-back', '← All projects')
  back.addEventListener('click', () => cb.onBack())
  root.append(back)

  if (detail === null) {
    root.append(el('div', 'proj-empty', 'Project not found.'))
    return root
  }

  // Header: name + branch + dirty + path
  const head = el('div', 'proj-detail-head')
  head.append(el('h2', 'proj-detail-name', detail.name))
  if (detail.branch) head.append(el('span', 'proj-branch', detail.branch))
  if (detail.dirty === true) {
    const d = el('span', 'proj-dirty', '●')
    d.title = 'Uncommitted changes'
    head.append(d)
  }
  root.append(head)
  root.append(el('div', 'proj-detail-path', detail.path))

  // Branch / worktrees
  root.append(el('div', 'proj-section-title', detail.worktrees.length > 1 ? 'Worktrees' : 'Branch'))
  if (!detail.isGit) {
    root.append(el('div', 'proj-empty', 'Not a git repository.'))
  } else if (detail.worktrees.length === 0) {
    root.append(
      el('div', 'proj-empty', detail.branch ? `On branch ${detail.branch}` : 'No worktree info.'),
    )
  } else {
    const list = el('div', 'proj-wt-list')
    for (const wt of detail.worktrees) list.append(makeWorktreeRow(wt))
    root.append(list)
  }

  // Active sessions
  const running = detail.sessions.filter((s) => !s.exited)
  root.append(el('div', 'proj-section-title', `Active sessions (${running.length})`))
  if (running.length === 0) {
    root.append(el('div', 'proj-empty', 'No running sessions — start one below.'))
  } else {
    const list = el('div', 'proj-detail-sessions')
    for (const s of running) list.append(makeDetailSessionRow(s, hooks.onEnterSession, cb.onKill))
    root.append(list)
  }

  // Launchers
  root.append(el('div', 'proj-section-title', 'Start'))
  root.append(makeLauncherRow(detail, hooks))

  return root
}

/* ── Mount ───────────────────────────────────────────────────────────────── */

export function mountProjects(host: HTMLElement, hooks: ProjectsHooks): ProjectsPanel {
  const root = el('div', 'proj-panel')
  root.style.display = 'none'
  host.appendChild(root)

  // Search box
  const searchWrap = el('div', 'proj-search-wrap')
  const searchInput = document.createElement('input')
  searchInput.className = 'proj-search'
  searchInput.type = 'search'
  searchInput.placeholder = 'Filter projects…'
  searchInput.setAttribute('aria-label', 'Filter projects')
  searchWrap.append(searchInput)
  root.append(searchWrap)

  const grid = el('div', 'proj-grid')
  root.append(grid)

  const detailEl = el('div', 'proj-detail')
  detailEl.style.display = 'none'
  root.append(detailEl)

  let allProjects: ProjectInfo[] = []
  let favs: Set<string> = getFavs()
  let timer: ReturnType<typeof setInterval> | null = null
  let view: 'grid' | 'detail' = 'grid'
  let detailPath: string | null = null

  function applyView(): void {
    const isGrid = view === 'grid'
    searchWrap.style.display = isGrid ? '' : 'none'
    grid.style.display = isGrid ? '' : 'none'
    detailEl.style.display = isGrid ? 'none' : 'block'
  }

  function openDetail(p: string): void {
    view = 'detail'
    detailPath = p
    applyView()
    void refresh()
  }

  function closeDetail(): void {
    view = 'grid'
    detailPath = null
    applyView()
    void refresh()
  }

  function renderGrid(): void {
    const filtered = filterProjects(allProjects, searchInput.value)
    const sorted = sortProjects(filtered, favs)

    grid.replaceChildren()

    if (sorted.length === 0) {
      const msg =
        allProjects.length === 0
          ? 'No projects found. Check PROJECT_ROOTS configuration.'
          : 'No projects match your search.'
      grid.append(el('div', 'proj-empty', msg))
      return
    }

    for (const p of sorted) {
      grid.append(
        makeProjectCard(
          p,
          favs,
          hooks,
          (path) => {
            favs = toggleFav(favs, path)
            saveFavs(favs)
            renderGrid()
          },
          openDetail,
        ),
      )
    }
  }

  function renderDetail(detail: ProjectDetail | null): void {
    detailEl.replaceChildren(
      renderProjectDetail(detail, hooks, {
        onBack: closeDetail,
        onKill: (id) => {
          void killSession(id).then(() => {
            if (view === 'detail') void refresh()
          })
        },
      }),
    )
  }

  async function refresh(): Promise<void> {
    if (view === 'detail' && detailPath !== null) {
      renderDetail(await fetchProjectDetail(detailPath))
      return
    }
    allProjects = await fetchProjects()
    favs = getFavs()
    renderGrid()
  }

  searchInput.addEventListener('input', () => renderGrid())

  return {
    setVisible(v: boolean): void {
      root.style.display = v ? 'block' : 'none'
      if (v) {
        // Re-entering the chooser always lands on the grid (never a stale detail).
        view = 'grid'
        detailPath = null
        applyView()
        void refresh()
        if (timer === null) {
          timer = setInterval(() => {
            if (root.style.display !== 'none') void refresh()
          }, REFRESH_MS)
        }
      } else {
        if (timer !== null) {
          clearInterval(timer)
          timer = null
        }
      }
    },
    refresh(): void {
      void refresh()
    },
  }
}