import { useEffect, useState } from 'react'
import type { Stats } from '../lib/api'
import { cssContentUrl, sendTestAlertNotification, type ColorScheme, type CssEntry } from '../lib/api'
import { useSettingsPanel } from '../lib/useSettingsPanel'
import { useDocsNav, type DocsTarget } from '../lib/docsNav'
import { DocsPanel } from './Docs'
import { HelpIcon } from './HelpIcon'
import { BUILTIN_THEMES, downloadThemeFile, generateThemeCss, parseThemeCss } from '../lib/themes'

type PanelName = 'settings' | 'docs' | null

const PANEL_TITLES: Record<Exclude<PanelName, null>, string> = {
  settings: 'Settings',
  docs: 'Docs',
}

/** Mirrors the backend's `profile::DEFAULT_PROFILE_NAME` — always exists, can't be deleted. */
const DEFAULT_PROFILE_NAME = 'Default'

const COLOR_SCHEMES: ColorScheme[] = [
  'system',
  'light',
  'dark',
  'red',
  'green',
  'blue',
  'yellow',
  'pink',
  'orange',
]

export function NavMenu({ stats }: { stats: Stats | null }) {
  const [openPanel, setOpenPanel] = useState<PanelName>(null)
  const panel = useSettingsPanel()
  const docsNav = useDocsNav()
  const [docsPanelTarget, setDocsPanelTarget] = useState<DocsTarget | null>(null)

  function togglePanel(name: PanelName) {
    setOpenPanel((current) => (current === name ? null : name))
  }

  // A "?" icon always opens Docs to its section and flashes it, even if Docs is already open elsewhere — hence forcing `openPanel` here rather than toggling.
  useEffect(() => {
    if (!docsNav.target) return
    setOpenPanel('docs')
    setDocsPanelTarget(docsNav.target)
  }, [docsNav.target])

  // Opening Docs via this button (not a "?" icon) has no forced section or flash, so clear any pending help-triggered target.
  function handleDocsButtonClick() {
    togglePanel('docs')
    setDocsPanelTarget(null)
  }

  return (
    <div className="flex h-full">
      <div className="flex h-full w-48 shrink-0 flex-col justify-between border-r border-border p-3">
        <div>
          <div className="mb-4 text-lg font-semibold text-text">ottyl</div>
          <PresetsDropdown panel={panel} />
          <nav className="mt-2 flex flex-col gap-1 text-sm text-text-muted">
            <button
              type="button"
              onClick={() => togglePanel('settings')}
              className={`rounded px-2 py-1 text-left hover:bg-surface-2 ${
                openPanel === 'settings' ? 'bg-surface-2 text-text' : ''
              }`}
            >
              Settings
            </button>
            <button
              type="button"
              onClick={handleDocsButtonClick}
              className={`rounded px-2 py-1 text-left hover:bg-surface-2 ${
                openPanel === 'docs' ? 'bg-surface-2 text-text' : ''
              }`}
            >
              Docs
            </button>
          </nav>
        </div>
        <div className="text-xs text-text-subtle">
          {stats ? (
            <>
              <div>{stats.log_count} logs</div>
              <div>
                seq {stats.first_sequence ?? 0}–{stats.last_sequence ?? 0}
              </div>
              <div>{stats.approx_bytes_total.toLocaleString()} bytes</div>
            </>
          ) : (
            <div>connecting…</div>
          )}
        </div>
      </div>

      {openPanel && (
        <div
          className={`fixed inset-y-0 left-48 z-20 flex flex-col overflow-y-auto border-r border-border bg-surface-1 p-4 shadow-xl ${
            openPanel === 'docs' ? 'w-[32rem]' : 'w-80'
          }`}
        >
          <div className="mb-3 flex items-center justify-between">
            <div className="flex items-center gap-1.5">
              <h2 className="text-sm font-semibold text-text">{PANEL_TITLES[openPanel]}</h2>
              {openPanel === 'settings' && <HelpIcon sectionId="settings" label="Help: Settings" />}
            </div>
            <button
              type="button"
              onClick={() => setOpenPanel(null)}
              className="rounded px-1.5 text-text-subtle hover:bg-surface-2 hover:text-text"
              aria-label="Close panel"
            >
              ✕
            </button>
          </div>
          {panel.error && openPanel !== 'docs' && (
            <div className="mb-3 rounded border border-danger-border bg-danger-bg/50 px-2 py-1 text-xs text-danger-text-strong">
              {panel.error}
            </div>
          )}
          {openPanel === 'settings' && <SettingsPanel panel={panel} />}
          {openPanel === 'docs' && <DocsPanel target={docsPanelTarget} />}
        </div>
      )}
    </div>
  )
}

/// Replaces the old Presets side-panel tab: a compact dropdown of profiles plus "+" (create a copy of
/// the active profile, prompting for its name) and "×" (delete the active profile — disabled for
/// `Default`, which can never be deleted).
function PresetsDropdown({ panel }: { panel: ReturnType<typeof useSettingsPanel> }) {
  const activeProfile = panel.settings?.active_profile ?? null

  async function handleCreate() {
    const name = window.prompt('New profile name (copies the current profile):')?.trim()
    if (!name) return
    await panel.addProfile(name)
    await panel.switchProfile(name)
  }

  async function handleDelete() {
    if (!activeProfile || activeProfile === DEFAULT_PROFILE_NAME) return
    await panel.removeProfile(activeProfile)
  }

  return (
    <div className="flex items-center gap-1">
      <select
        value={activeProfile ?? ''}
        onChange={(e) => panel.switchProfile(e.target.value)}
        className="min-w-0 flex-1 rounded border border-border-soft bg-surface-1 px-1.5 py-1 text-xs text-text focus:border-border-strong focus:outline-none"
      >
        {activeProfile === null && <option value="">No active profile</option>}
        {panel.profiles.map((profile) => (
          <option key={profile.name} value={profile.name}>
            {profile.name}
          </option>
        ))}
      </select>
      <button
        type="button"
        onClick={handleCreate}
        className="shrink-0 rounded border border-border-soft px-1.5 py-1 text-xs text-text-secondary hover:bg-surface-2"
        aria-label="New profile"
        title="New profile (copies the current one)"
      >
        +
      </button>
      <button
        type="button"
        onClick={handleDelete}
        disabled={!activeProfile || activeProfile === DEFAULT_PROFILE_NAME}
        className="shrink-0 rounded border border-border-soft px-1.5 py-1 text-xs text-text-secondary hover:bg-surface-2 disabled:cursor-not-allowed disabled:opacity-40"
        aria-label="Delete current profile"
        title={activeProfile === DEFAULT_PROFILE_NAME ? "The Default profile can't be deleted" : 'Delete current profile'}
      >
        ×
      </button>
      <HelpIcon sectionId="presets" label="Help: Presets" />
    </div>
  )
}

function SettingsPanel({ panel }: { panel: ReturnType<typeof useSettingsPanel> }) {
  const [maxLogsInput, setMaxLogsInput] = useState('')
  const [cssFilename, setCssFilename] = useState('')
  const [cssContent, setCssContent] = useState('')
  const [cssUploadError, setCssUploadError] = useState<string | null>(null)
  const [cssLinkUrl, setCssLinkUrl] = useState('')
  const [ntfyTopicInput, setNtfyTopicInput] = useState('')
  const [ntfyServerInput, setNtfyServerInput] = useState('')
  const [ntfyTestError, setNtfyTestError] = useState<string | null>(null)
  const [ntfyTestSuccess, setNtfyTestSuccess] = useState(false)
  const [ntfyTesting, setNtfyTesting] = useState(false)

  useEffect(() => {
    setMaxLogsInput(panel.settings?.max_logs != null ? String(panel.settings.max_logs) : '')
  }, [panel.settings?.max_logs])

  useEffect(() => {
    setNtfyTopicInput(panel.settings?.ntfy_topic ?? '')
    setNtfyServerInput(panel.settings?.ntfy_server ?? '')
  }, [panel.settings?.ntfy_topic, panel.settings?.ntfy_server])

  function handleNtfyTopicBlur() {
    panel.setNtfySink(ntfyTopicInput.trim() || null, panel.settings?.ntfy_server ?? null)
  }

  function handleNtfyServerBlur() {
    panel.setNtfySink(panel.settings?.ntfy_topic ?? null, ntfyServerInput.trim() || null)
  }

  async function handleNtfyTest() {
    setNtfyTestError(null)
    setNtfyTestSuccess(false)
    if (!ntfyTopicInput.trim()) {
      setNtfyTestError('Enter a topic to send a test notification.')
      return
    }
    setNtfyTesting(true)
    try {
      await sendTestAlertNotification(ntfyTopicInput.trim(), ntfyServerInput.trim() || null)
      setNtfyTestSuccess(true)
    } catch (err) {
      setNtfyTestError(err instanceof Error ? err.message : 'Failed to send test notification')
    } finally {
      setNtfyTesting(false)
    }
  }

  function handleMaxLogsBlur() {
    const trimmed = maxLogsInput.trim()
    if (trimmed === '') {
      panel.setMaxLogs(null)
      return
    }
    const parsed = Number(trimmed)
    if (!Number.isFinite(parsed) || parsed <= 0) {
      setMaxLogsInput(panel.settings?.max_logs != null ? String(panel.settings.max_logs) : '')
      return
    }
    panel.setMaxLogs(Math.floor(parsed))
  }

  async function handleCssFileChange(e: React.ChangeEvent<HTMLInputElement>) {
    const file = e.target.files?.[0]
    if (!file) return
    setCssFilename(file.name)
    setCssContent(await file.text())
    setCssUploadError(null)
  }

  // Every imported/linked stylesheet is always a selectable theme (ticket 020), so it's always
  // validated against the canonical `--c-*` variable set before it's sent.
  async function handleCssImport(e: React.FormEvent) {
    e.preventDefault()
    setCssUploadError(null)
    if (!cssFilename.trim() || !cssContent.trim()) return
    const { missing } = parseThemeCss(cssContent)
    if (missing.length > 0) {
      setCssUploadError(`Missing variable${missing.length > 1 ? 's' : ''}: ${missing.join(', ')}`)
      return
    }
    await panel.importCssEntry(cssFilename.trim(), cssContent)
    setCssFilename('')
    setCssContent('')
  }

  async function handleCssLink(e: React.FormEvent) {
    e.preventDefault()
    if (!cssLinkUrl.trim()) return
    await panel.linkCssEntry(cssLinkUrl.trim())
    setCssLinkUrl('')
  }

  function downloadBuiltinTheme(name: string) {
    const vars = BUILTIN_THEMES[name]
    if (!vars) return
    downloadThemeFile(`${name}.css`, generateThemeCss(vars))
  }

  async function downloadCssEntry(entry: CssEntry) {
    if (entry.kind === 'imported') {
      const res = await fetch(cssContentUrl(entry.id))
      const text = await res.text()
      downloadThemeFile(entry.filename ?? `${entry.id}.css`, text)
    } else if (entry.path_or_url) {
      window.open(entry.path_or_url, '_blank', 'noopener')
    }
  }

  return (
    <div className="flex flex-col gap-5 text-sm text-text-secondary">
      <section>
        <h3 className="mb-2 text-xs font-semibold uppercase tracking-wide text-text-subtle">Colour scheme</h3>
        <div className="flex flex-wrap gap-1">
          {COLOR_SCHEMES.map((scheme) => (
            <div key={scheme} className="flex items-center">
              <button
                type="button"
                onClick={() => panel.setColorScheme(scheme)}
                className={`rounded-l border px-2 py-1 text-xs capitalize ${
                  !panel.activeCustomTheme && panel.settings?.color_scheme === scheme
                    ? 'border-border-strong bg-surface-2 text-text'
                    : 'border-border-soft text-text-muted hover:bg-surface-2'
                }`}
              >
                {scheme}
              </button>
              {scheme !== 'system' && (
                <button
                  type="button"
                  onClick={() => downloadBuiltinTheme(scheme)}
                  className="rounded-r border border-l-0 border-border-soft px-1.5 py-1 text-xs text-text-faint hover:bg-surface-2 hover:text-text"
                  aria-label={`Download ${scheme} theme`}
                  title="Download as .css"
                >
                  ↓
                </button>
              )}
            </div>
          ))}
        </div>
      </section>

      <section>
        <h3 className="mb-2 text-xs font-semibold uppercase tracking-wide text-text-subtle">Log retention</h3>
        <div className="flex items-center gap-2">
          <input
            type="number"
            min={1}
            placeholder="Unlimited"
            value={maxLogsInput}
            onChange={(e) => setMaxLogsInput(e.target.value)}
            onBlur={handleMaxLogsBlur}
            className="w-28 rounded border border-border-soft bg-surface-1 px-2 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
          />
          <span className="text-xs text-text-faint">max logs kept in memory (blank = unlimited)</span>
        </div>
      </section>

      <section>
        <div className="mb-2 flex items-center gap-1.5">
          <h3 className="text-xs font-semibold uppercase tracking-wide text-text-subtle">Ntfy sink</h3>
          <HelpIcon sectionId="alerts" label="Help: Ntfy sink" />
        </div>
        <div className="flex flex-col gap-2">
          <div className="flex items-center gap-1.5">
            <input
              type="text"
              placeholder="https://ntfy.sh"
              value={ntfyServerInput}
              onChange={(e) => setNtfyServerInput(e.target.value)}
              onBlur={handleNtfyServerBlur}
              className="min-w-0 flex-[2] rounded border border-border-soft bg-surface-1 px-2 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
            />
            <span className="shrink-0 text-xs text-text-faint" aria-hidden="true">/</span>
            <input
              type="text"
              placeholder="topic"
              value={ntfyTopicInput}
              onChange={(e) => setNtfyTopicInput(e.target.value)}
              onBlur={handleNtfyTopicBlur}
              className="min-w-0 flex-1 rounded border border-border-soft bg-surface-1 px-2 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
            />
          </div>
          {ntfyTestError && <div className="text-xs text-danger-text-strong">{ntfyTestError}</div>}
          {ntfyTestSuccess && <div className="text-xs text-text-secondary">Test notification sent.</div>}
          <button
            type="button"
            onClick={handleNtfyTest}
            disabled={ntfyTesting}
            className="self-start rounded border border-border-soft px-2 py-1 text-xs text-text hover:bg-surface-2 disabled:opacity-50"
          >
            {ntfyTesting ? 'Sending…' : 'Send test notification'}
          </button>
        </div>
      </section>

      <section>
        <div className="mb-2 flex items-center gap-1.5">
          <h3 className="text-xs font-semibold uppercase tracking-wide text-text-subtle">CSS</h3>
          <span className="text-[11px] text-text-faint">
            imported/linked stylesheets — each one becomes a selectable alternative to the built-in colour schemes
            above
          </span>
        </div>
        {panel.cssEntries.length === 0 ? (
          <div className="mb-2 text-xs text-text-faint">No CSS configured.</div>
        ) : (
          <ul className="mb-2 flex flex-col gap-1">
            {panel.cssEntries.map((entry) => (
              <li
                key={entry.id}
                className="flex items-center justify-between rounded border border-border px-2 py-1 text-xs"
              >
                <div className="min-w-0 flex-1">
                  <button
                    type="button"
                    onClick={() => panel.setCustomTheme(entry.id)}
                    className={`block w-full truncate text-left capitalize ${
                      panel.activeCustomTheme?.id === entry.id ? 'text-text' : 'text-text-muted hover:text-text'
                    }`}
                  >
                    {entry.filename ?? entry.path_or_url}
                  </button>
                  <div className="text-[10px] uppercase text-text-faint">{entry.kind}</div>
                </div>
                <div className="ml-2 flex shrink-0 items-center gap-1">
                  <button
                    type="button"
                    onClick={() => downloadCssEntry(entry)}
                    className="rounded px-1.5 text-text-subtle hover:bg-surface-2 hover:text-text"
                    aria-label={`Download ${entry.filename ?? entry.path_or_url}`}
                    title="Download as .css"
                  >
                    ↓
                  </button>
                  {entry.kind === 'imported' ? (
                    <button
                      type="button"
                      onClick={() => panel.removeCssEntry(entry.id)}
                      className="rounded px-1.5 text-text-subtle hover:bg-surface-2 hover:text-danger-text"
                      aria-label={`Delete ${entry.filename}`}
                    >
                      delete
                    </button>
                  ) : (
                    <span className="text-text-faintest" title="Linked CSS isn't deletable here">
                      —
                    </span>
                  )}
                </div>
              </li>
            ))}
          </ul>
        )}

        <form onSubmit={handleCssImport} className="flex flex-col gap-2">
          <input
            type="file"
            accept=".css,text/css"
            onChange={handleCssFileChange}
            className="text-xs text-text-muted file:mr-2 file:rounded file:border file:border-border-soft file:bg-surface-2 file:px-2 file:py-1 file:text-text"
          />
          <input
            type="text"
            placeholder="enter name"
            value={cssFilename}
            onChange={(e) => setCssFilename(e.target.value)}
            className="rounded border border-border-soft bg-surface-1 px-2 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
          />
          <textarea
            placeholder="Paste CSS content here"
            value={cssContent}
            onChange={(e) => setCssContent(e.target.value)}
            rows={4}
            className="resize-y rounded border border-border-soft bg-surface-1 px-2 py-1 font-mono text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
          />
          {cssUploadError && <div className="text-xs text-danger-text-strong">{cssUploadError}</div>}
          <button
            type="submit"
            className="rounded border border-border-soft px-2 py-1 text-xs text-text hover:bg-surface-2"
          >
            Import
          </button>
        </form>

        <form onSubmit={handleCssLink} className="mt-2 flex flex-col gap-2">
          <input
            type="text"
            placeholder="https://example.com/style.css"
            value={cssLinkUrl}
            onChange={(e) => setCssLinkUrl(e.target.value)}
            className="min-w-0 flex-1 rounded border border-border-soft bg-surface-1 px-2 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
          />
          <div className="flex items-center gap-2">
            <button
              type="submit"
              className="shrink-0 rounded border border-border-soft px-2 py-1 text-xs text-text hover:bg-surface-2"
            >
              Link
            </button>
          </div>
        </form>
      </section>
    </div>
  )
}