'use client';

import { useEffect, useState } from 'react';
import { useRouter, useSearchParams } from 'next/navigation';
import { apiFetch } from '@/lib/api';
import { Button } from '@/components/ui/button';
import { Input, Label, Textarea } from '@/components/input';
import { StreamingLogs } from '@/components/streaming-logs';
import { InstallSnippets } from '@/components/install-snippets';
import { CodeBlock } from '@/components/code-block';
import { Loader2, RotateCcw, X } from 'lucide-react';

const EXAMPLE_PROMPTS = [
  {
    label: 'Echo / demo (no external API)',
    text: 'Build a simple echo server with two tools: echo (string in, same string back) and now (returns current UTC timestamp). No external API needed.',
  },
  {
    label: 'Notion search',
    text: 'Search and read pages from our Notion workspace via the Notion API. Tools: search_pages(query), get_page_content(page_id). Auth: NOTION_API_KEY.',
  },
  {
    label: 'Postgres reader',
    text: 'Read-only Postgres reader for the users and orders tables at db.example.com. One tool per table: list_users(limit), list_orders(limit, customer_id?). Auth: DATABASE_URL.',
  },
  {
    label: 'Wrap our REST API',
    text: 'Wrap our internal HTTP API at api.acme.com — endpoints /search?q= and /lookup?id=. Tools: search(query), lookup(id). Auth: ACME_API_TOKEN.',
  },
  {
    label: 'Stripe charges (read-only)',
    text: 'Stripe charges and customers, read-only. Tools: list_recent_charges(limit), get_customer(customer_id). Auth: STRIPE_SECRET_KEY.',
  },
];

type Step = 'prompt' | 'analyzing' | 'confirm' | 'building' | 'done';

interface PreviewTool {
  name: string;
  description: string;
  inputSchema: Record<string, unknown>;
}

interface PreviewResponse {
  previewId: string;
  source: 'claude' | 'mock';
  spec: {
    name: string;
    description?: string;
    tools: PreviewTool[];
    requiredSecrets: string[];
    scopes: string[];
  };
}

interface EditableTool {
  name: string;
  description: string;
  inputSchemaJson: string;
  schemaError: string | null;
}

interface EditableSpec {
  tools: EditableTool[];
  requiredSecrets: string[];
}

interface BuildResult {
  serverId: string;
  publicUrl: string | null;
}

function specToEditable(spec: PreviewResponse['spec']): EditableSpec {
  return {
    tools: spec.tools.map((t) => ({
      name: t.name,
      description: t.description,
      inputSchemaJson: JSON.stringify(t.inputSchema, null, 2),
      schemaError: null,
    })),
    requiredSecrets: [...spec.requiredSecrets],
  };
}

export default function NewServerPage() {
  const router = useRouter();
  const [step, setStep] = useState<Step>('prompt');

  const [prompt, setPrompt] = useState('');
  const [name, setName] = useState('');
  const [slug, setSlug] = useState('');

  const [preview, setPreview] = useState<PreviewResponse | null>(null);
  const [editable, setEditable] = useState<EditableSpec | null>(null);
  const [secretValues, setSecretValues] = useState<Record<string, string>>({});

  const [error, setError] = useState<string | null>(null);
  const [buildId, setBuildId] = useState<string | null>(null);
  const [serverId, setServerId] = useState<string | null>(null);
  const [result, setResult] = useState<BuildResult | null>(null);
  const [forkedTemplateId, setForkedTemplateId] = useState<string | null>(null);
  const [forkedTemplateTitle, setForkedTemplateTitle] = useState<string | null>(null);

  const searchParams = useSearchParams();
  const templateSlug = searchParams.get('template');

  const trySlug = (n: string) =>
    n.toLowerCase().replace(/[^a-z0-9-]+/g, '-').replace(/^-+|-+$/g, '').slice(0, 32);

  // Fork-from-template flow: skip Step 1, jump straight to Step 2 with the template's spec
  useEffect(() => {
    if (!templateSlug || preview) return;
    let cancelled = false;
    setStep('analyzing');
    (async () => {
      try {
        const res = await apiFetch<{
          previewId: string;
          templateId: string;
          template: {
            slug: string;
            title: string;
            shortDescription: string;
            tools: PreviewTool[];
            requiredSecrets: Array<{
              key: string;
              description: string;
              howToGetUrl?: string;
            }>;
          };
        }>(`/v1/templates/${templateSlug}/fork`, { method: 'POST', body: '{}' });
        if (cancelled) return;
        setName(res.template.title);
        setSlug(trySlug(res.template.title));
        setPrompt(`Fork of "${res.template.title}" template.`);
        setForkedTemplateId(res.templateId);
        setForkedTemplateTitle(res.template.title);
        setPreview({
          previewId: res.previewId,
          source: 'mock',
          spec: {
            name: res.template.title,
            description: res.template.shortDescription,
            tools: res.template.tools,
            requiredSecrets: res.template.requiredSecrets.map((s) => s.key),
            scopes: [],
          },
        });
        setEditable(null);
        setStep('confirm');
      } catch (e) {
        if (cancelled) return;
        const detail = (e as { detail?: { error?: string } }).detail;
        setError(detail?.error ?? (e as Error).message);
        setStep('prompt');
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [templateSlug, preview]);

  useEffect(() => {
    if (preview && !editable) {
      const e = specToEditable(preview.spec);
      setEditable(e);
      const initial: Record<string, string> = {};
      for (const key of e.requiredSecrets) initial[key] = '';
      setSecretValues(initial);
    }
  }, [preview, editable]);

  async function analyze() {
    setError(null);
    if (prompt.trim().length < 10) {
      setError('Prompt must be at least 10 characters.');
      return;
    }
    if (!name || !slug) {
      setError('Name and slug are required.');
      return;
    }
    setStep('analyzing');
    try {
      const res = await apiFetch<PreviewResponse>('/v1/servers/preview', {
        method: 'POST',
        body: JSON.stringify({ prompt }),
      });
      setPreview(res);
      setEditable(null); // will re-init via useEffect
      setStep('confirm');
    } catch (e) {
      const detail = (e as { detail?: { error?: string; detail?: string } }).detail;
      setError(detail?.detail ?? detail?.error ?? (e as Error).message);
      setStep('prompt');
    }
  }

  function updateTool(i: number, patch: Partial<EditableTool>) {
    setEditable((prev) => {
      if (!prev) return prev;
      const tools = [...prev.tools];
      const cur = tools[i];
      if (!cur) return prev;
      tools[i] = { ...cur, ...patch };
      return { ...prev, tools };
    });
  }

  function updateToolSchema(i: number, json: string) {
    let schemaError: string | null = null;
    try {
      const parsed = JSON.parse(json);
      if (typeof parsed !== 'object' || parsed === null || Array.isArray(parsed)) {
        schemaError = 'Schema must be a JSON object.';
      }
    } catch (e) {
      schemaError = `JSON parse error: ${(e as Error).message}`;
    }
    updateTool(i, { inputSchemaJson: json, schemaError });
  }

  function addSecret() {
    setEditable((prev) =>
      prev ? { ...prev, requiredSecrets: [...prev.requiredSecrets, ''] } : prev,
    );
  }

  function removeSecret(idx: number) {
    setEditable((prev) => {
      if (!prev) return prev;
      const removedKey = prev.requiredSecrets[idx];
      const next = prev.requiredSecrets.filter((_, i) => i !== idx);
      const sv = { ...secretValues };
      if (removedKey) delete sv[removedKey];
      setSecretValues(sv);
      return { ...prev, requiredSecrets: next };
    });
  }

  function updateSecretKey(idx: number, newKey: string) {
    const cleaned = newKey.toUpperCase().replace(/[^A-Z0-9_]/g, '');
    setEditable((prev) => {
      if (!prev) return prev;
      const prevKey = prev.requiredSecrets[idx];
      const next = [...prev.requiredSecrets];
      next[idx] = cleaned;
      const sv = { ...secretValues };
      if (prevKey && prevKey in sv) {
        sv[cleaned] = sv[prevKey] ?? '';
        if (prevKey !== cleaned) delete sv[prevKey];
      }
      setSecretValues(sv);
      return { ...prev, requiredSecrets: next };
    });
  }

  function resetEdits() {
    if (preview) setEditable(specToEditable(preview.spec));
  }

  async function build() {
    setError(null);
    if (!preview || !editable) return;

    // Validate every schema parses
    const badTool = editable.tools.find((t) => t.schemaError);
    if (badTool) {
      setError(`Fix schema for "${badTool.name}": ${badTool.schemaError}`);
      return;
    }

    // Validate secret keys: non-empty + UPPER_SNAKE_CASE
    for (const key of editable.requiredSecrets) {
      if (!key) {
        setError('Empty secret name. Remove the row or fill it in.');
        return;
      }
      if (!/^[A-Z][A-Z0-9_]*$/.test(key)) {
        setError(`Secret name "${key}" must be UPPER_SNAKE_CASE.`);
        return;
      }
    }

    // Validate filled secret values for present keys
    const filledSecrets: Record<string, string> = {};
    for (const k of editable.requiredSecrets) {
      const v = secretValues[k] ?? '';
      if (v.trim()) filledSecrets[k] = v;
    }
    const missing = editable.requiredSecrets.filter((k) => !filledSecrets[k]);
    if (missing.length > 0) {
      setError(`Fill values for: ${missing.join(', ')} — or remove from the list.`);
      return;
    }

    const specEdit = {
      tools: editable.tools.map((t) => ({
        name: t.name,
        description: t.description,
        inputSchema: JSON.parse(t.inputSchemaJson),
      })),
      requiredSecrets: editable.requiredSecrets,
    };

    try {
      const res = await apiFetch<{ server: { id: string }; build: { id: string } }>(
        '/v1/servers',
        {
          method: 'POST',
          body: JSON.stringify({
            name,
            slug,
            prompt,
            secrets: filledSecrets,
            previewId: preview.previewId,
            // Don't send specEdit when forking — the template's spec + pre-rendered code
            // are already in the Redis cache. Edits would invalidate the impls.
            ...(forkedTemplateId ? { templateId: forkedTemplateId } : { specEdit }),
          }),
        },
      );
      setBuildId(res.build.id);
      setServerId(res.server.id);
      setStep('building');
    } catch (e) {
      const detail = (e as { detail?: { error?: string; detail?: unknown } }).detail;
      setError(detail?.error ?? (e as Error).message);
    }
  }

  const stepNumber = step === 'prompt' ? 1 : step === 'analyzing' || step === 'confirm' ? 2 : 3;
  const hasSchemaErrors = editable?.tools.some((t) => t.schemaError);
  const editsDirty =
    preview && editable
      ? JSON.stringify(specToEditable(preview.spec)) !== JSON.stringify(editable)
      : false;

  return (
    <div className="mx-auto max-w-3xl px-6 py-8">
      <div className="flex items-baseline justify-between">
        <h1 className="text-[22px] font-semibold tracking-tight">New MCP server</h1>
        <div className="mono text-[11px] tracking-wider text-[--color-fg-subtle]">
          STEP {stepNumber} / 3
        </div>
      </div>

      {step === 'prompt' && (
        <div className="mt-7 space-y-5">
          <div className="space-y-1.5">
            <Label htmlFor="prompt">Describe what your tool should do</Label>
            <Textarea
              id="prompt"
              rows={5}
              value={prompt}
              onChange={(e) => setPrompt(e.target.value)}
              placeholder="A sentence is enough. Mention which APIs you need, which scopes, what the AI client should be able to do."
            />
            <p className="text-[12px] leading-relaxed text-[--color-fg-subtle]">
              Next step we&apos;ll show you exactly which tools we&apos;ll expose and let you tweak
              the spec before we build.
            </p>
            <div className="flex flex-wrap gap-1.5 pt-1">
              {EXAMPLE_PROMPTS.map((p) => (
                <button
                  type="button"
                  key={p.label}
                  onClick={() => setPrompt(p.text)}
                  className="rounded-full border border-[--color-border] bg-[--color-bg-subtle] px-2.5 py-1 text-[11.5px] text-[--color-fg-muted] transition-colors hover:border-[--color-border-strong] hover:text-[--color-fg]"
                >
                  {p.label}
                </button>
              ))}
            </div>
          </div>

          <div className="grid gap-3 md:grid-cols-2">
            <div className="space-y-1.5">
              <Label htmlFor="name">Name</Label>
              <Input
                id="name"
                value={name}
                onChange={(e) => {
                  setName(e.target.value);
                  if (!slug || slug === trySlug(name)) setSlug(trySlug(e.target.value));
                }}
                placeholder="Notion Reader"
              />
            </div>
            <div className="space-y-1.5">
              <Label htmlFor="slug" hint="becomes subdomain / id">Slug</Label>
              <Input
                id="slug"
                value={slug}
                onChange={(e) => setSlug(trySlug(e.target.value))}
                placeholder="notion-reader"
              />
            </div>
          </div>

          {error && <p className="text-[12.5px] text-[--color-danger]">{error}</p>}

          <div className="flex justify-end gap-2">
            <Button variant="ghost" size="md" onClick={() => router.push('/servers')}>
              Cancel
            </Button>
            <Button variant="primary" size="md" onClick={analyze}>
              Analyze →
            </Button>
          </div>
        </div>
      )}

      {step === 'analyzing' && (
        <div className="mt-10 panel p-8 text-center">
          <Loader2 className="mx-auto animate-spin text-[--color-fg-muted]" size={20} />
          <p className="mt-4 text-[13px]">Analyzing your prompt…</p>
          <p className="mt-1 text-[12px] text-[--color-fg-subtle]">
            Claude Opus 4.7 is parsing the spec. Usually 20–40 seconds.
          </p>
        </div>
      )}

      {step === 'confirm' && preview && editable && (
        <div className="mt-7 space-y-6">
          {forkedTemplateTitle && (
            <div className="panel-subtle p-3 flex items-center justify-between">
              <div className="text-[12.5px]">
                Forking <span className="mono font-semibold">{forkedTemplateTitle}</span> — fill in
                your own credentials below. The template author never sees them.
              </div>
              <a
                href={`/templates/${templateSlug}`}
                target="_blank"
                rel="noreferrer"
                className="text-[11.5px] text-[--color-fg-muted] underline hover:text-[--color-fg]"
              >
                Template ↗
              </a>
            </div>
          )}
          <div className="panel p-4">
            <div className="flex items-baseline justify-between">
              <h2 className="text-[14px] font-semibold tracking-tight">Confirm what we&apos;ll build</h2>
              <div className="flex items-center gap-3">
                {editsDirty && (
                  <button
                    type="button"
                    onClick={resetEdits}
                    className="inline-flex items-center gap-1 text-[11px] text-[--color-fg-muted] transition-colors hover:text-[--color-fg]"
                  >
                    <RotateCcw size={11} /> reset edits
                  </button>
                )}
                <span className="mono text-[10.5px] text-[--color-fg-subtle]">
                  spec via {preview.source}
                </span>
              </div>
            </div>
            <p className="mt-1 text-[12.5px] text-[--color-fg-muted]">{preview.spec.description}</p>
            <p className="mt-3 text-[11.5px] leading-relaxed text-[--color-fg-subtle]">
              Edit tool names, descriptions or input schemas inline. Renaming parameters may
              require an <span className="mono">Iterate</span> after build to update the
              implementation — the existing impl references the original names.
            </p>
          </div>

          <div>
            <h3 className="text-[13px] font-semibold tracking-tight">
              Tools ({editable.tools.length})
            </h3>
            <div className="mt-2 space-y-3">
              {editable.tools.map((tool, i) => (
                <div key={i} className="panel p-3 space-y-2.5">
                  <div className="grid gap-2 md:grid-cols-[1fr_auto]">
                    <Input
                      value={tool.name}
                      onChange={(e) => updateTool(i, { name: e.target.value })}
                      placeholder="snake_case_tool_name"
                      className="mono"
                    />
                    <span className="mono self-center text-[10.5px] text-[--color-fg-subtle]">
                      {Object.keys(safeJsonObject(tool.inputSchemaJson)).length} param
                      {Object.keys(safeJsonObject(tool.inputSchemaJson)).length === 1 ? '' : 's'}
                    </span>
                  </div>
                  <Textarea
                    rows={2}
                    value={tool.description}
                    onChange={(e) => updateTool(i, { description: e.target.value })}
                    placeholder="What the AI client sees — one clear sentence."
                  />
                  <div className="space-y-1">
                    <Label hint="JSON object — keys are param names, values describe each param">
                      Input schema
                    </Label>
                    <Textarea
                      rows={Math.min(12, Math.max(3, tool.inputSchemaJson.split('\n').length))}
                      value={tool.inputSchemaJson}
                      onChange={(e) => updateToolSchema(i, e.target.value)}
                      className="mono text-[12px]"
                      spellCheck={false}
                    />
                    {tool.schemaError && (
                      <p className="text-[11.5px] text-[--color-danger]">{tool.schemaError}</p>
                    )}
                  </div>
                </div>
              ))}
            </div>
          </div>

          <div>
            <h3 className="text-[13px] font-semibold tracking-tight">
              Credentials we need
            </h3>
            <p className="mt-1 text-[12px] leading-relaxed text-[--color-fg-muted]">
              AES-256-GCM encrypted at rest, injected as env vars at runtime. Remove if your
              implementation doesn&apos;t actually use one.
            </p>
            <div className="mt-3 space-y-2">
              {editable.requiredSecrets.length === 0 && (
                <p className="text-[12.5px] text-[--color-fg-muted]">
                  No credentials. This server runs self-contained.
                </p>
              )}
              {editable.requiredSecrets.map((key, idx) => (
                <div key={idx} className="grid grid-cols-[180px_1fr_auto] items-start gap-2">
                  <Input
                    value={key}
                    onChange={(e) => updateSecretKey(idx, e.target.value)}
                    placeholder="MY_API_KEY"
                    className="mono"
                  />
                  <Input
                    type="password"
                    value={secretValues[key] ?? ''}
                    onChange={(e) => setSecretValues((s) => ({ ...s, [key]: e.target.value }))}
                    placeholder="paste value"
                  />
                  <button
                    type="button"
                    onClick={() => removeSecret(idx)}
                    aria-label="Remove"
                    className="inline-flex h-8 items-center justify-center rounded-md border border-[--color-border] px-2 text-[--color-fg-muted] transition-colors hover:text-[--color-fg]"
                  >
                    <X size={13} />
                  </button>
                </div>
              ))}
              <Button variant="ghost" size="sm" onClick={addSecret}>
                + Add credential
              </Button>
            </div>
          </div>

          {preview.spec.scopes.length > 0 && (
            <div>
              <h3 className="text-[13px] font-semibold tracking-tight">OAuth scopes</h3>
              <div className="mt-2 flex flex-wrap gap-1.5">
                {preview.spec.scopes.map((s) => (
                  <span
                    key={s}
                    className="mono rounded-full border border-[--color-border] bg-[--color-bg-subtle] px-2 py-0.5 text-[11px] text-[--color-fg-muted]"
                  >
                    {s}
                  </span>
                ))}
              </div>
            </div>
          )}

          {error && <p className="text-[12.5px] text-[--color-danger]">{error}</p>}

          <div className="flex justify-end gap-2">
            <Button variant="ghost" size="md" onClick={() => setStep('prompt')}>
              ← Back
            </Button>
            <Button
              variant="primary"
              size="md"
              onClick={build}
              disabled={Boolean(hasSchemaErrors)}
            >
              Build server →
            </Button>
          </div>
        </div>
      )}

      {step === 'building' && buildId && (
        <div className="mt-7 space-y-4">
          <p className="text-[13px] text-[--color-fg-muted]">
            Building your server. Logs stream live over WebSocket from the generator.
          </p>
          <StreamingLogs
            buildId={buildId}
            onDone={(status, publicUrl) => {
              if (status === 'success') {
                setResult({ serverId: serverId!, publicUrl });
                setStep('done');
              } else {
                setError(`Build ${status}`);
              }
            }}
          />
          {error && <p className="text-[12.5px] text-[--color-danger]">{error}</p>}
        </div>
      )}

      {step === 'done' && result && (
        <div className="mt-7 space-y-6">
          <div className="panel p-4">
            <div className="flex items-baseline justify-between">
              <h2 className="text-[14px] font-semibold tracking-tight">Your server is live</h2>
              <span className="mono text-[11px] text-emerald-300">200 OK</span>
            </div>
            <p className="mt-1 text-[12.5px] text-[--color-fg-muted]">
              OAuth-protected Streamable HTTP endpoint:
            </p>
            <div className="mt-3">
              <CodeBlock code={`${result.publicUrl}/mcp`} label="endpoint" />
            </div>
          </div>

          {result.publicUrl && (
            <div>
              <h2 className="text-[14px] font-semibold tracking-tight">Install</h2>
              <p className="mt-1 text-[12.5px] text-[--color-fg-muted]">
                Drop this into your client. OAuth handshake runs automatically on first use.
              </p>
              <div className="mt-3">
                <InstallSnippets input={{ name, slug, publicUrl: result.publicUrl }} />
              </div>
            </div>
          )}

          <div className="flex justify-end gap-2">
            <Button
              variant="secondary"
              size="md"
              onClick={() => router.push(`/servers/${result.serverId}`)}
            >
              Open server →
            </Button>
          </div>
        </div>
      )}
    </div>
  );
}

function safeJsonObject(s: string): Record<string, unknown> {
  try {
    const parsed = JSON.parse(s);
    if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
      return parsed as Record<string, unknown>;
    }
  } catch {}
  return {};
}