import { useEffect, useState } from 'react';
import { Archive, Maximize2, Minimize2, X } from 'lucide-react';
import { toast } from 'sonner';
import { api } from '@/api/client';
import type { Project, Session } from '@/api/types';
import { Button } from '@/components/ui/button';
import { Textarea } from '@/components/ui/textarea';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from '@/components/ui/dialog';
import { ModelPicker } from '@/components/ModelPicker';
import { ThemePicker } from '@/components/ThemePicker';
import { cn } from '@/lib/utils';

type Section = 'session' | 'project' | 'theme';

interface Props {
  session: Session;
  project: Project;
  maximized: boolean;
  onToggleMaximize: () => void;
  onClose: () => void;
  isMobile: boolean;
}

// v1.9: hand-rolled Switch primitive. No shadcn switch in the existing
// ui/ set and the dispatch said don't pnpm dlx for v1.9 either. Single
// purpose — clicking flips aria-checked + calls onCheckedChange.
function Switch({
  checked,
  onCheckedChange,
  disabled,
  id,
}: {
  checked: boolean;
  onCheckedChange: (v: boolean) => void;
  disabled?: boolean;
  id?: string;
}) {
  return (
    <button
      id={id}
      type="button"
      role="switch"
      aria-checked={checked}
      disabled={disabled}
      onClick={() => onCheckedChange(!checked)}
      className={cn(
        'relative inline-flex h-5 w-9 shrink-0 cursor-pointer items-center rounded-full transition-colors',
        checked ? 'bg-primary' : 'bg-muted',
        disabled && 'opacity-50 cursor-not-allowed',
      )}
    >
      <span
        className={cn(
          'inline-block h-4 w-4 transform rounded-full bg-background transition-transform',
          checked ? 'translate-x-[1.125rem]' : 'translate-x-0.5',
        )}
      />
    </button>
  );
}

export function SettingsPane({ session, project, maximized, onToggleMaximize, onClose, isMobile }: Props) {
  const [activeSection, setActiveSection] = useState<Section>('session');

  return (
    <div className="flex flex-col h-full min-h-0">
      <div className="flex items-center gap-2 border-b border-border bg-muted/20 px-3 py-1.5 shrink-0">
        <div className="flex items-center gap-1 flex-1 min-w-0">
          {(['session', 'project', 'theme'] as const).map((s) => (
            <button
              key={s}
              type="button"
              onClick={() => setActiveSection(s)}
              className={cn(
                'text-xs px-2 py-1 rounded capitalize',
                activeSection === s
                  ? 'bg-background text-foreground'
                  : 'text-muted-foreground hover:bg-muted',
              )}
            >
              {s}
            </button>
          ))}
        </div>
        {!isMobile && (
          <button
            type="button"
            onClick={onToggleMaximize}
            className="inline-flex items-center justify-center p-1 rounded text-muted-foreground hover:bg-muted hover:text-foreground"
            aria-label={maximized ? 'Restore' : 'Maximize'}
            title={maximized ? 'Restore (Esc)' : 'Maximize'}
          >
            {maximized ? <Minimize2 size={14} /> : <Maximize2 size={14} />}
          </button>
        )}
        <button
          type="button"
          onClick={onClose}
          className="inline-flex items-center justify-center p-1 rounded text-muted-foreground hover:bg-muted hover:text-foreground max-md:min-h-[44px] max-md:min-w-[44px]"
          aria-label="Close settings"
          title="Close (Esc)"
        >
          <X size={14} />
        </button>
      </div>

      <div className="flex-1 overflow-y-auto">
        <div className="max-w-[720px] mx-auto w-full px-4 py-4 space-y-6">
          {activeSection === 'session' && <SessionSection session={session} project={project} />}
          {activeSection === 'project' && <ProjectSection project={project} />}
          {activeSection === 'theme' && <ThemePicker />}
        </div>
      </div>
    </div>
  );
}

function SessionSection({ session, project }: { session: Session; project: Project }) {
  const [name, setName] = useState(session.name);
  const [systemPrompt, setSystemPrompt] = useState(session.system_prompt);
  // v1.9: tri-state on the wire (null = inherit). UI surfaces a 3-way toggle
  // via "Inherit project default" checkbox plus the override switch.
  const [webSearch, setWebSearch] = useState<boolean | null>(session.web_search_enabled);
  const [saving, setSaving] = useState(false);
  // v1.9: bulk-archive chats. Two-step: openChatsCount → confirm dialog →
  // archiveAllChats. Server publishes one chat_archived frame per id so
  // useSidebar / chat lists update incrementally.
  const [archiveOpen, setArchiveOpen] = useState(false);
  const [archiveCount, setArchiveCount] = useState(0);
  const [archiving, setArchiving] = useState(false);

  useEffect(() => {
    setName(session.name);
    setSystemPrompt(session.system_prompt);
    setWebSearch(session.web_search_enabled);
  }, [session.id, session.name, session.system_prompt, session.web_search_enabled]);

  const dirty =
    name !== session.name ||
    systemPrompt !== session.system_prompt ||
    webSearch !== session.web_search_enabled;

  const effectiveWebSearch = webSearch ?? project.default_web_search_enabled;
  const projectPreview = project.default_system_prompt.trim().slice(0, 200);

  async function save() {
    if (saving) return;
    setSaving(true);
    try {
      await api.sessions.update(session.id, {
        name: name.trim() || session.name,
        system_prompt: systemPrompt,
        web_search_enabled: webSearch,
      });
      toast.success('Session saved');
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'save failed');
    } finally {
      setSaving(false);
    }
  }

  async function resetSystemPrompt() {
    if (saving) return;
    setSaving(true);
    try {
      await api.sessions.update(session.id, { system_prompt: '' });
      toast.success('Reset to project default');
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'reset failed');
    } finally {
      setSaving(false);
    }
  }

  async function openArchiveDialog() {
    if (archiving) return;
    try {
      const { count } = await api.sessions.openChatsCount(session.id);
      if (count === 0) {
        toast('No open chats to archive.');
        return;
      }
      setArchiveCount(count);
      setArchiveOpen(true);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'failed to count chats');
    }
  }

  async function confirmArchive() {
    if (archiving) return;
    setArchiving(true);
    try {
      const { archived } = await api.sessions.archiveAllChats(session.id);
      toast.success(`Archived ${archived} chat${archived === 1 ? '' : 's'}`);
      setArchiveOpen(false);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'archive failed');
    } finally {
      setArchiving(false);
    }
  }

  return (
    <div className="space-y-6">
      <div className="space-y-1.5">
        <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
          Session name
        </label>
        <input
          type="text"
          value={name}
          onChange={(e) => setName(e.target.value)}
          className="w-full bg-background border border-border rounded px-2 py-1.5 text-sm outline-none focus:border-ring"
        />
      </div>

      <div className="space-y-1.5">
        <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
          Model
        </label>
        <div className="inline-flex items-center rounded-full bg-muted/40 hover:bg-muted/70 px-1">
          <ModelPicker
            value={session.model}
            onChange={async (model) => {
              try {
                await api.sessions.update(session.id, { model });
                toast.success('Model updated');
              } catch (err) {
                toast.error(err instanceof Error ? err.message : 'failed to set model');
              }
            }}
          />
        </div>
      </div>

      <div className="space-y-1.5">
        <div className="flex items-center justify-between gap-3">
          <label htmlFor="session-web-search" className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
            Web search and fetch
          </label>
          <Switch
            id="session-web-search"
            checked={effectiveWebSearch}
            onCheckedChange={(v) => setWebSearch(v)}
          />
        </div>
        <div className="flex items-center gap-2 text-xs text-muted-foreground">
          <input
            type="checkbox"
            id="session-web-search-inherit"
            checked={webSearch === null}
            onChange={(e) => setWebSearch(e.target.checked ? null : project.default_web_search_enabled)}
          />
          <label htmlFor="session-web-search-inherit" className="cursor-pointer">
            Inherit project default ({project.default_web_search_enabled ? 'on' : 'off'})
          </label>
        </div>
        <p className="text-xs text-muted-foreground italic">
          Plumbed for Batch 8 (web_search tool). No effect yet.
        </p>
      </div>

      <div className="space-y-1.5">
        <div className="flex items-center justify-between gap-3">
          <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
            System prompt
          </label>
          <button
            type="button"
            onClick={() => void resetSystemPrompt()}
            disabled={saving || session.system_prompt === ''}
            className="text-xs text-muted-foreground hover:text-foreground disabled:opacity-40 disabled:cursor-not-allowed"
          >
            Reset to project default
          </button>
        </div>
        <Textarea
          value={systemPrompt}
          onChange={(e) => setSystemPrompt(e.target.value)}
          rows={6}
          className="resize-y min-h-[120px] max-h-[60vh]"
          placeholder="Per-session override (optional). Empty = inherit project default."
        />
        {systemPrompt.trim().length === 0 && projectPreview.length > 0 && (
          <p className="text-xs text-muted-foreground">
            Falls back to project default: <span className="italic">{projectPreview}{projectPreview.length === 200 ? '…' : ''}</span>
          </p>
        )}
      </div>

      <div className="flex justify-end gap-2">
        <Button onClick={() => void save()} disabled={!dirty || saving}>
          {saving ? 'Saving…' : 'Save'}
        </Button>
      </div>

      <div className="border-t pt-4">
        <Button
          variant="outline"
          onClick={() => void openArchiveDialog()}
          disabled={archiving}
          className="gap-1.5"
        >
          <Archive size={14} /> Archive all chats
        </Button>
      </div>

      <Dialog open={archiveOpen} onOpenChange={(open) => { if (!archiving) setArchiveOpen(open); }}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Archive all chats?</DialogTitle>
            <DialogDescription>
              Archive {archiveCount} open chat{archiveCount === 1 ? '' : 's'} in this session?
              Archived chats stay accessible via the archive view.
            </DialogDescription>
          </DialogHeader>
          <DialogFooter>
            <Button variant="outline" onClick={() => setArchiveOpen(false)} disabled={archiving}>
              Cancel
            </Button>
            <Button onClick={() => void confirmArchive()} disabled={archiving}>
              {archiving ? 'Archiving…' : `Archive ${archiveCount}`}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}

function ProjectSection({ project }: { project: Project }) {
  const [name, setName] = useState(project.name);
  const [defaultPrompt, setDefaultPrompt] = useState(project.default_system_prompt);
  const [defaultWebSearch, setDefaultWebSearch] = useState(project.default_web_search_enabled);
  const [saving, setSaving] = useState(false);
  // v1.9: bulk-archive sessions. Same shape as the chats-archive flow in
  // SessionSection — count, confirm, fire.
  const [archiveOpen, setArchiveOpen] = useState(false);
  const [archiveCount, setArchiveCount] = useState(0);
  const [archiving, setArchiving] = useState(false);

  useEffect(() => {
    setName(project.name);
    setDefaultPrompt(project.default_system_prompt);
    setDefaultWebSearch(project.default_web_search_enabled);
  }, [
    project.id,
    project.name,
    project.default_system_prompt,
    project.default_web_search_enabled,
  ]);

  const dirty =
    name !== project.name ||
    defaultPrompt !== project.default_system_prompt ||
    defaultWebSearch !== project.default_web_search_enabled;

  async function save() {
    if (saving) return;
    setSaving(true);
    try {
      await api.projects.update(project.id, {
        name: name.trim() || project.name,
        default_system_prompt: defaultPrompt,
        default_web_search_enabled: defaultWebSearch,
      });
      toast.success('Project saved');
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'save failed');
    } finally {
      setSaving(false);
    }
  }

  async function clearDefaultPrompt() {
    if (saving) return;
    setSaving(true);
    try {
      await api.projects.update(project.id, { default_system_prompt: '' });
      toast.success('Cleared');
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'clear failed');
    } finally {
      setSaving(false);
    }
  }

  async function openArchiveDialog() {
    if (archiving) return;
    try {
      const { count } = await api.projects.openSessionsCount(project.id);
      if (count === 0) {
        toast('No open sessions to archive.');
        return;
      }
      setArchiveCount(count);
      setArchiveOpen(true);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'failed to count sessions');
    }
  }

  async function confirmArchive() {
    if (archiving) return;
    setArchiving(true);
    try {
      const { archived } = await api.projects.archiveAllSessions(project.id);
      toast.success(`Archived ${archived} session${archived === 1 ? '' : 's'}`);
      setArchiveOpen(false);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : 'archive failed');
    } finally {
      setArchiving(false);
    }
  }

  return (
    <div className="space-y-6">
      <div className="space-y-1.5">
        <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
          Project name
        </label>
        <input
          type="text"
          value={name}
          onChange={(e) => setName(e.target.value)}
          className="w-full bg-background border border-border rounded px-2 py-1.5 text-sm outline-none focus:border-ring"
        />
      </div>

      <div className="space-y-1.5">
        <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
          Root path
        </label>
        <div className="font-mono text-xs text-muted-foreground bg-muted/40 rounded px-2 py-1.5 select-all">
          {project.path}
        </div>
      </div>

      <div className="space-y-1.5">
        <div className="flex items-center justify-between gap-3">
          <label htmlFor="project-default-web-search" className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
            Default web search
          </label>
          <Switch
            id="project-default-web-search"
            checked={defaultWebSearch}
            onCheckedChange={setDefaultWebSearch}
          />
        </div>
        <p className="text-xs text-muted-foreground italic">
          Applies to new sessions only. Plumbed for Batch 8.
        </p>
      </div>

      <div className="space-y-1.5">
        <div className="flex items-center justify-between gap-3">
          <label className="text-xs font-medium uppercase tracking-wide text-muted-foreground">
            Default system prompt
          </label>
          <button
            type="button"
            onClick={() => void clearDefaultPrompt()}
            disabled={saving || project.default_system_prompt === ''}
            className="text-xs text-muted-foreground hover:text-foreground disabled:opacity-40 disabled:cursor-not-allowed"
          >
            Clear
          </button>
        </div>
        <Textarea
          value={defaultPrompt}
          onChange={(e) => setDefaultPrompt(e.target.value)}
          rows={6}
          className="resize-y min-h-[120px] max-h-[60vh]"
          placeholder="Prepended to every new session's system prompt (when its own is empty). Empty = no project default."
        />
      </div>

      <p className="text-xs text-muted-foreground">
        Existing sessions are not affected by changes here.
      </p>

      <div className="flex justify-end gap-2">
        <Button onClick={() => void save()} disabled={!dirty || saving}>
          {saving ? 'Saving…' : 'Save'}
        </Button>
      </div>

      <div className="border-t pt-4">
        <Button
          variant="outline"
          onClick={() => void openArchiveDialog()}
          disabled={archiving}
          className="gap-1.5"
        >
          <Archive size={14} /> Archive all sessions
        </Button>
      </div>

      <Dialog open={archiveOpen} onOpenChange={(open) => { if (!archiving) setArchiveOpen(open); }}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Archive all sessions?</DialogTitle>
            <DialogDescription>
              Archive {archiveCount} open session{archiveCount === 1 ? '' : 's'} in this project?
              Archived sessions stay accessible via the archive view.
            </DialogDescription>
          </DialogHeader>
          <DialogFooter>
            <Button variant="outline" onClick={() => setArchiveOpen(false)} disabled={archiving}>
              Cancel
            </Button>
            <Button onClick={() => void confirmArchive()} disabled={archiving}>
              {archiving ? 'Archiving…' : `Archive ${archiveCount}`}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}