// Signal-conditioned views in this file must use <Show>, never a
// signal-conditioned early return (`if (signal()) return <X/>`). Early
// returns in SolidJS run once at mount and never re-execute when signals
// change — see Projects.md §4.1.
import { createMemo, createSignal, Show } from "solid-js";

import { sendMessage } from "../App";
import { PeachWordmark } from "../components/PeachMark";
import {
  parseImportSource,
  type ImportParseResult,
} from "../../shared/import";
import type { VaultEntry } from "../../shared/types";
import { CJKImportView } from "./CJKImport";

interface ImportProps {
  mode?: "existing" | "onboarding";
  replacesExistingVault?: boolean;
  onBack: () => void;
  onImport: () => void | Promise<void>;
}

type ImportMergeMode = "add" | "replace";

export function ImportView(props: ImportProps) {
  const [showCjkImport, setShowCjkImport] = createSignal(false);
  return (
    <Show
      when={showCjkImport()}
      fallback={
        <MainImportView
          mode={props.mode}
          replacesExistingVault={props.replacesExistingVault}
          onBack={props.onBack}
          onImport={props.onImport}
          onOpenCjk={() => setShowCjkImport(true)}
        />
      }
    >
      <CJKImportView
        mode="existing"
        onBack={() => setShowCjkImport(false)}
        onDone={async () => {
          setShowCjkImport(false);
          await props.onImport();
        }}
      />
    </Show>
  );
}

function MainImportView(props: ImportProps & { onOpenCjk: () => void }) {
  const mode = () => props.mode ?? "existing";

  const [preview, setPreview] = createSignal<ImportParseResult | null>(null);
  const [rawImport, setRawImport] = createSignal<string | null>(null);
  const [backupPassword, setBackupPassword] = createSignal("");
  const [masterPassword, setMasterPassword] = createSignal("");
  const [masterConfirm, setMasterConfirm] = createSignal("");
  const [importing, setImporting] = createSignal(false);
  const [error, setError] = createSignal<string | null>(null);
  const [mergeMode, setMergeMode] = createSignal<ImportMergeMode>("add");
  const [awaitingReplaceConfirm, setAwaitingReplaceConfirm] = createSignal(false);
  const [importProgress, setImportProgress] = createSignal<{ current: number; total: number } | null>(null);
  const [duplicateWarning, setDuplicateWarning] = createSignal<number>(0);
  const [existingCount, setExistingCount] = createSignal<number>(0);

  const needsBackupPassword = createMemo(() => preview()?.requiresPassword ?? false);
  const needsMasterPassword = createMemo(() => mode() === "onboarding");
  const masterPasswordReady = createMemo(
    () =>
      masterPassword().length >= 8 && masterPassword() === masterConfirm()
  );

  async function refreshExistingCount() {
    if (mode() !== "existing") return;
    const res = await sendMessage({ type: "GET_ENTRIES" });
    const list = (res as { ok: boolean; data?: VaultEntry[] }).data ?? [];
    setExistingCount(list.length);
  }

  void refreshExistingCount();

  async function parseSource(text: string, password?: string) {
    try {
      const result = await parseImportSource(text, password);
      setPreview(result);
      setError(null);
      if (result.format === "unknown") {
        setError(
          "We couldn't recognise this file format. Peach supports: Peach JSON backups, Bitwarden JSON/CSV, Proton Pass JSON/CSV, 1Password JSON, and generic browser CSV exports."
        );
      }
      return result;
    } catch (err) {
      const message = err instanceof Error ? err.message : String(err);
      setPreview(null);
      setError(getImportErrorCopy(message));
      return null;
    }
  }

  async function handleFileSelect(event: Event) {
    const file = (event.target as HTMLInputElement).files?.[0];
    if (!file) return;

    setPreview(null);
    setRawImport(null);
    setBackupPassword("");
    setError(null);
    setAwaitingReplaceConfirm(false);

    const text = await file.text();
    setRawImport(text);
    await parseSource(text);
  }

  async function handleUnlockBackup() {
    const raw = rawImport();
    if (!raw || !backupPassword().trim()) return;
    await parseSource(raw, backupPassword());
  }

  async function countDuplicates(incoming: ImportParseResult["entries"]): Promise<number> {
    if (incoming.length === 0) return 0;
    const res = await sendMessage({ type: "GET_ENTRIES" });
    const existing = ((res as { ok: boolean; data?: VaultEntry[] }).data ?? []).filter((e) => !e.deletedAt);
    const keyOf = (title?: string, url?: string, username?: string) =>
      `${(title ?? "").toLowerCase()}|${(url ?? "").toLowerCase()}|${(username ?? "").toLowerCase()}`;
    const existingKeys = new Set(existing.map((e) => keyOf(e.title, e.url, e.username)));
    let dupes = 0;
    for (const entry of incoming) {
      const u = "username" in entry ? entry.username : undefined;
      const url = "url" in entry ? entry.url : undefined;
      if (existingKeys.has(keyOf(entry.title, url, u))) dupes += 1;
    }
    return dupes;
  }

  async function handleImport() {
    const currentPreview = preview();
    if (!currentPreview) return;

    if (needsBackupPassword() && !backupPassword().trim()) {
      setError("Enter the backup password used for this export.");
      return;
    }

    if (needsMasterPassword()) {
      if (masterPassword().length < 8) {
        setError("Master password must be at least 8 characters.");
        return;
      }
      if (!masterPasswordReady()) {
        setError("Master passwords do not match.");
        return;
      }
    }

    if (mode() === "existing" && mergeMode() === "replace" && !awaitingReplaceConfirm()) {
      setAwaitingReplaceConfirm(true);
      return;
    }

    setImporting(true);
    setError(null);
    setDuplicateWarning(0);
    setImportProgress(null);

    try {
      // ⚠️  Guard: verify entries exist BEFORE touching any vault.
      // Without this, CREATE_VAULT would already have wiped the old vault
      // before we discover the file has nothing importable.
      if (currentPreview.entries.length === 0) {
        throw new Error("NO_ENTRIES_IMPORTED");
      }

      if (needsMasterPassword()) {
        const createResponse = await sendMessage({
          type: "CREATE_VAULT",
          payload: { password: masterPassword() },
        });
        if (!(createResponse as { ok: boolean }).ok) {
          throw new Error("CREATE_VAULT_FAILED");
        }
      }

      if (mode() === "existing" && mergeMode() === "replace") {
        const clearRes = await sendMessage({ type: "CLEAR_VAULT_ENTRIES" });
        if (!(clearRes as { ok: boolean }).ok) {
          throw new Error("CLEAR_VAULT_FAILED");
        }
      }

      let dupes = 0;
      if (mode() === "existing" && mergeMode() === "add") {
        dupes = await countDuplicates(currentPreview.entries);
      }

      let imported = 0;
      setImportProgress({ current: 0, total: currentPreview.entries.length });

      const batchRes = await sendMessage({
        type: "BATCH_ADD_ENTRIES",
        payload: { entries: currentPreview.entries },
      });

      if ((batchRes as { ok: boolean }).ok) {
        imported = ((batchRes as { ok: boolean; data?: VaultEntry[] }).data ?? []).length;
        setImportProgress({ current: imported, total: currentPreview.entries.length });
      } else {
        // Fallback to sequential
        for (const entry of currentPreview.entries) {
          const response = await sendMessage({
            type: "ADD_ENTRY",
            payload: entry,
          });
          if ((response as { ok: boolean }).ok) imported += 1;
          setImportProgress({ current: imported, total: currentPreview.entries.length });
        }
      }

      if (imported === 0) {
        throw new Error("NO_ENTRIES_IMPORTED");
      }

      setDuplicateWarning(dupes);
      await props.onImport();
    } catch (err) {
      const message = err instanceof Error ? err.message : String(err);
      setError(getImportErrorCopy(message));
      setImporting(false);
      setImportProgress(null);
      return;
    }

    setImporting(false);
    setImportProgress(null);
  }

  return (
    <div class={mode() === "onboarding" ? "peach-lock-view" : "peach-overlay-view ov-enter-right"}>
      <Show
        when={mode() === "onboarding"}
        fallback={
          <div class="peach-overlay-header">
            <button
              class="peach-btn peach-btn--ghost peach-btn--sm peach-icon-btn"
              onClick={props.onBack}
              aria-label="Back"
            >
              <svg
                width="7"
                height="12"
                viewBox="0 0 7 12"
                fill="none"
                stroke="currentColor"
                stroke-width="1.1"
                stroke-linecap="round"
                stroke-linejoin="round"
              >
                <path d="M6 1L1 6L6 11" />
              </svg>
            </button>
            <span class="peach-overlay-title">import</span>
            <div class="peach-overlay-spacer"></div>
          </div>
        }
      >
        <div class="peach-lock-view-header">
          <PeachWordmark class="peach-wordmark-wrap" />
          <button
            class="peach-lock-restore-link"
            onClick={props.onBack}
            disabled={importing()}
          >
            ‹ back
          </button>
        </div>
      </Show>

      <div class="peach-settings-body">
        <div class="peach-settings-group peach-restore-group">
          <p class="peach-settings-label">
            {mode() === "onboarding" ? "bring data into peach" : "import passwords"}
          </p>
          <p class="peach-restore-copy">
            {mode() === "onboarding"
              ? "Import a Peach backup, FIDO credential-exchange export, Proton Pass export, Bitwarden export, or a common browser CSV. We'll create a fresh local vault first."
              : "Supports Peach encrypted backups, FIDO credential-exchange passkeys, Proton Pass, Bitwarden, and common browser CSV exports."}
          </p>

          <Show when={mode() === "onboarding" && props.replacesExistingVault}>
            <div class="peach-restore-warning">
              Restoring now replaces the locked local vault on this device with
              a fresh one from your backup or export file.
            </div>
          </Show>

          <div class="peach-provider-chips">
            <span class="peach-provider-chip">Peach JSON</span>
            <span class="peach-provider-chip">FIDO passkeys</span>
            <span class="peach-provider-chip">Proton Pass CSV/JSON</span>
            <span class="peach-provider-chip">Bitwarden CSV/JSON</span>
            <span class="peach-provider-chip">1Password JSON</span>
            <span class="peach-provider-chip">Chrome / Edge / Safari CSV</span>
          </div>
        </div>

        <Show when={mode() === "existing"}>
          <div class="peach-settings-group">
            <p class="peach-settings-label">restore from CJK phrase</p>
            <p class="peach-restore-copy">
              Use a Peach CJK backup phrase instead of a file.
            </p>
            <button
              class="peach-btn peach-btn--subtle peach-btn--sm"
              onClick={props.onOpenCjk}
            >
              Restore from CJK phrase
            </button>
          </div>
        </Show>

        <div class="peach-settings-group">
          <p class="peach-settings-label">select file</p>
          <input
            class="peach-restore-file"
            type="file"
            accept=".csv,.json"
            onChange={(event) => void handleFileSelect(event)}
          />
        </div>

        <Show when={needsBackupPassword()}>
          <div class="peach-settings-group">
            <p class="peach-settings-label">unlock backup</p>
            <p class="peach-restore-copy">
              Enter the password used when you created this encrypted Peach JSON
              backup.
            </p>
            <input
              class="peach-restore-input"
              type="password"
              placeholder="backup password"
              value={backupPassword()}
              onInput={(event) =>
                setBackupPassword((event.target as HTMLInputElement).value)
              }
              onBlur={() => { if (backupPassword().trim()) void handleUnlockBackup(); }}
              onKeyDown={(event) => {
                if (event.key === "Enter") {
                  event.preventDefault();
                  void handleUnlockBackup();
                }
              }}
            />
            <div class="peach-settings-actions">
              <button
                class="peach-btn peach-btn--subtle peach-btn--sm"
                onClick={() => void handleUnlockBackup()}
                disabled={!backupPassword().trim()}
              >
                Decrypt →
              </button>
            </div>
          </div>
        </Show>

        <Show when={preview() && !needsBackupPassword() && preview()!.format !== "unknown"}>
          <div class="peach-settings-group">
            <p class="peach-settings-label">{preview()!.label}</p>
            <div class="peach-import-summary">
              Found <strong>{preview()!.entries.length}</strong>{" "}
              entr{preview()!.entries.length === 1 ? "y" : "ies"}
              {preview()!.skippedItems > 0
                ? `. ${preview()!.skippedItems} skipped because no password was present.`
                : "."}
            </div>

            <div class="peach-import-preview">
              {preview()!.entries.slice(0, 8).map((entry) => (
                <div class="peach-import-preview-row">
                  <span class="peach-import-preview-title">{entry.title}</span>
                  <span class="peach-import-preview-meta">
                    {entry.type === "passkey"
                      ? `${entry.userName || "passkey"} • ${entry.rpId || "site"}`
                      : entry.type === "note"
                        ? "secure note"
                        : entry.username || entry.url || "password item"}
                  </span>
                </div>
              ))}
              <Show when={preview()!.entries.length > 8}>
                <div class="peach-import-preview-more">
                  ...and {preview()!.entries.length - 8} more
                </div>
              </Show>
            </div>
          </div>
        </Show>

        <Show when={mode() === "existing" && preview() && !needsBackupPassword() && preview()!.format !== "unknown" && preview()!.entries.length > 0}>
          <div class="peach-settings-group">
            <p class="peach-settings-label">merge or replace</p>
            <label class="peach-import-choice">
              <input
                type="radio"
                name="merge-mode"
                value="add"
                checked={mergeMode() === "add"}
                onChange={() => { setMergeMode("add"); setAwaitingReplaceConfirm(false); }}
              />
              <span class="peach-import-choice-main">
                <span class="peach-import-choice-label">Add to existing vault</span>
                <span class="peach-import-choice-sub">
                  This will add {preview()!.entries.length} entries to your existing {existingCount()}.
                </span>
              </span>
            </label>
            <label class="peach-import-choice">
              <input
                type="radio"
                name="merge-mode"
                value="replace"
                checked={mergeMode() === "replace"}
                onChange={() => setMergeMode("replace")}
              />
              <span class="peach-import-choice-main">
                <span class="peach-import-choice-label">Replace vault</span>
                <span class="peach-import-choice-sub">
                  This will replace your {existingCount()} entries with {preview()!.entries.length} imported ones.
                </span>
              </span>
            </label>
            <Show when={awaitingReplaceConfirm()}>
              <div class="peach-restore-warning" style="margin-top:6px">
                Replace forever? This cannot be undone.
              </div>
            </Show>
          </div>
        </Show>

        <Show when={needsMasterPassword() && preview() && !needsBackupPassword() && preview()!.format !== "unknown"}>
          <div class="peach-settings-group">
            <p class="peach-settings-label">new master password</p>
            <p class="peach-restore-copy">
              This password unlocks the Peach vault created on this device after
              import. It is separate from any export password.
            </p>
            <div class="peach-auth-grid">
              <input
                class="peach-restore-input"
                type="password"
                placeholder="new master password"
                value={masterPassword()}
                onInput={(event) =>
                  setMasterPassword((event.target as HTMLInputElement).value)
                }
              />
              <input
                class="peach-restore-input"
                type="password"
                placeholder="confirm master password"
                value={masterConfirm()}
                onInput={(event) =>
                  setMasterConfirm((event.target as HTMLInputElement).value)
                }
              />
            </div>
          </div>
        </Show>

        <Show when={error()}>
          <div class="peach-settings-group">
            <div class="peach-restore-error">{error()}</div>
          </div>
        </Show>

        <Show when={importing() && importProgress()}>
          <div class="peach-settings-group">
            <div class="peach-import-summary">
              Importing... [{importProgress()!.current} / {importProgress()!.total}]
            </div>
          </div>
        </Show>

        <Show when={duplicateWarning() > 0 && !importing()}>
          <div class="peach-settings-group">
            <div class="peach-restore-copy">
              {duplicateWarning()} {duplicateWarning() === 1 ? "entry appears" : "entries appear"} to be duplicates of existing ones. They were still imported — you can review and delete them in your vault.
            </div>
          </div>
        </Show>

        <Show when={preview() && !needsBackupPassword() && preview()!.format !== "unknown"}>
          <div class="peach-settings-group">
            <div class="peach-settings-actions">
              <button
                class="peach-btn peach-btn--subtle peach-btn--sm"
                onClick={() => void handleImport()}
                disabled={
                  importing() ||
                  preview()!.entries.length === 0 ||
                  (needsMasterPassword() && !masterPasswordReady())
                }
              >
                {importing()
                  ? "importing..."
                  : mode() === "onboarding"
                    ? `Create vault + import ${preview()!.entries.length}`
                    : mergeMode() === "replace"
                      ? awaitingReplaceConfirm()
                        ? "Yes, replace forever"
                        : `Replace vault with ${preview()!.entries.length}`
                      : `Import ${preview()!.entries.length}`}
              </button>
              <button
                class="peach-btn peach-btn--ghost peach-btn--sm"
                onClick={props.onBack}
                disabled={importing()}
              >
                Cancel
              </button>
            </div>
          </div>
        </Show>
      </div>
    </div>
  );
}

function getImportErrorCopy(error: string): string {
  switch (error) {
    case "UNSUPPORTED_IMPORT_FORMAT":
      return "Unrecognised file format. Use CSV, Bitwarden JSON, Proton Pass JSON/CSV, or a Peach encrypted backup.";
    case "INVALID_EXPORT_PASSWORD":
      return "Incorrect backup password. This is the password you chose when you exported the Peach JSON backup.";
    case "INVALID_PEACH_EXPORT":
      return "This Peach backup file looks corrupted or incomplete.";
    case "CREATE_VAULT_FAILED":
      return "Peach couldn't create a new local vault before importing.";
    case "CLEAR_VAULT_FAILED":
      return "Peach couldn't clear the existing vault before replacing it.";
    case "NO_ENTRIES_IMPORTED":
      return "No importable password entries were found in that file.";
    default:
      return error;
  }
}