import { useEffect, useMemo, useRef, useState, type ChangeEvent } from "react";
import { useMutation, useQueryClient } from "@tanstack/react-query";
import type {
  CompanyPortabilityCollisionStrategy,
  CompanyPortabilityPreviewResult,
  CompanyPortabilitySource,
} from "@paperclipai/shared";
import { useCompany } from "../context/CompanyContext";
import { useBreadcrumbs } from "../context/BreadcrumbContext";
import { useToast } from "../context/ToastContext";
import { companiesApi } from "../api/companies";
import { queryKeys } from "../lib/queryKeys";
import { MarkdownBody } from "../components/MarkdownBody";
import { Button } from "@/components/ui/button";
import { EmptyState } from "../components/EmptyState";
import { cn } from "../lib/utils";
import {
  Download,
  Github,
  Link2,
  Package,
  Upload,
} from "lucide-react";
import { Field } from "../components/agent-config-primitives";
import {
  type FileTreeNode,
  type FrontmatterData,
  buildFileTree,
  countFiles,
  collectAllPaths,
  parseFrontmatter,
  FRONTMATTER_FIELD_LABELS,
  PackageFileTree,
} from "../components/PackageFileTree";

// ── Import-specific helpers ───────────────────────────────────────────

/** Build a map from file path → planned action (create/update/skip) using the manifest + plan */
function buildActionMap(preview: CompanyPortabilityPreviewResult): Map<string, string> {
  const map = new Map<string, string>();
  const manifest = preview.manifest;

  for (const ap of preview.plan.agentPlans) {
    const agent = manifest.agents.find((a) => a.slug === ap.slug);
    if (agent) {
      const path = ensureMarkdownPath(agent.path);
      map.set(path, ap.action);
    }
  }

  for (const pp of preview.plan.projectPlans) {
    const project = manifest.projects.find((p) => p.slug === pp.slug);
    if (project) {
      const path = ensureMarkdownPath(project.path);
      map.set(path, pp.action);
    }
  }

  for (const ip of preview.plan.issuePlans) {
    const issue = manifest.issues.find((i) => i.slug === ip.slug);
    if (issue) {
      const path = ensureMarkdownPath(issue.path);
      map.set(path, ip.action);
    }
  }

  for (const skill of manifest.skills) {
    const path = ensureMarkdownPath(skill.path);
    map.set(path, "create");
    // Also mark skill file inventory
    for (const file of skill.fileInventory) {
      if (preview.files[file.path]) {
        map.set(file.path, "create");
      }
    }
  }

  // Company file
  if (manifest.company) {
    const path = ensureMarkdownPath(manifest.company.path);
    map.set(path, preview.plan.companyAction === "none" ? "skip" : preview.plan.companyAction);
  }

  return map;
}

function ensureMarkdownPath(p: string): string {
  return p.endsWith(".md") ? p : `${p}.md`;
}

const ACTION_COLORS: Record<string, string> = {
  create: "text-emerald-500 border-emerald-500/30",
  update: "text-amber-500 border-amber-500/30",
  overwrite: "text-red-500 border-red-500/30",
  replace: "text-red-500 border-red-500/30",
  skip: "text-muted-foreground border-border",
  none: "text-muted-foreground border-border",
};

function FrontmatterCard({ data }: { data: FrontmatterData }) {
  return (
    <div className="rounded-md border border-border bg-accent/20 px-4 py-3 mb-4">
      <dl className="grid grid-cols-[auto_minmax(0,1fr)] gap-x-4 gap-y-1.5 text-sm">
        {Object.entries(data).map(([key, value]) => (
          <div key={key} className="contents">
            <dt className="text-muted-foreground whitespace-nowrap py-0.5">
              {FRONTMATTER_FIELD_LABELS[key] ?? key}
            </dt>
            <dd className="py-0.5">
              {Array.isArray(value) ? (
                <div className="flex flex-wrap gap-1.5">
                  {value.map((item) => (
                    <span
                      key={item}
                      className="inline-flex items-center rounded-md border border-border bg-background px-2 py-0.5 text-xs"
                    >
                      {item}
                    </span>
                  ))}
                </div>
              ) : (
                <span>{value}</span>
              )}
            </dd>
          </div>
        ))}
      </dl>
    </div>
  );
}

// ── Import file tree customization ───────────────────────────────────

function renderImportFileExtra(node: FileTreeNode, checked: boolean) {
  if (!node.action) return null;
  const actionColor = ACTION_COLORS[node.action] ?? ACTION_COLORS.skip;
  return (
    <span className={cn(
      "shrink-0 rounded-full border px-2 py-0.5 text-[10px] uppercase tracking-wide",
      actionColor,
    )}>
      {checked ? node.action : "skip"}
    </span>
  );
}

function importFileRowClassName(_node: FileTreeNode, checked: boolean) {
  return !checked ? "opacity-50" : undefined;
}

// ── Preview pane ──────────────────────────────────────────────────────

function ImportPreviewPane({
  selectedFile,
  content,
  action,
}: {
  selectedFile: string | null;
  content: string | null;
  action: string | null;
}) {
  if (!selectedFile || content === null) {
    return (
      <EmptyState icon={Package} message="Select a file to preview its contents." />
    );
  }

  const isMarkdown = selectedFile.endsWith(".md");
  const parsed = isMarkdown ? parseFrontmatter(content) : null;
  const actionColor = action ? (ACTION_COLORS[action] ?? ACTION_COLORS.skip) : "";

  return (
    <div className="min-w-0">
      <div className="border-b border-border px-5 py-3">
        <div className="flex items-center justify-between gap-3">
          <div className="truncate font-mono text-sm">{selectedFile}</div>
          {action && (
            <span className={cn(
              "shrink-0 rounded-full border px-2 py-0.5 text-xs uppercase tracking-wide",
              actionColor,
            )}>
              {action}
            </span>
          )}
        </div>
      </div>
      <div className="min-h-[560px] px-5 py-5">
        {parsed ? (
          <>
            <FrontmatterCard data={parsed.data} />
            {parsed.body.trim() && <MarkdownBody>{parsed.body}</MarkdownBody>}
          </>
        ) : isMarkdown ? (
          <MarkdownBody>{content}</MarkdownBody>
        ) : (
          <pre className="overflow-x-auto whitespace-pre-wrap break-words border-0 bg-transparent p-0 font-mono text-sm text-foreground">
            <code>{content}</code>
          </pre>
        )}
      </div>
    </div>
  );
}

// ── Helpers ───────────────────────────────────────────────────────────

async function readLocalPackageSelection(fileList: FileList): Promise<{
  rootPath: string | null;
  files: Record<string, string>;
}> {
  const files: Record<string, string> = {};
  let rootPath: string | null = null;
  for (const file of Array.from(fileList)) {
    const relativePath =
      (file as File & { webkitRelativePath?: string }).webkitRelativePath?.replace(
        /\\/g,
        "/",
      ) || file.name;
    const isMarkdown = relativePath.endsWith(".md");
    const isPaperclipYaml =
      relativePath.endsWith(".paperclip.yaml") || relativePath.endsWith(".paperclip.yml");
    if (!isMarkdown && !isPaperclipYaml) continue;
    const topLevel = relativePath.split("/")[0] ?? null;
    if (!rootPath && topLevel) rootPath = topLevel;
    files[relativePath] = await file.text();
  }
  if (Object.keys(files).length === 0) {
    throw new Error("No package files were found in the selected folder.");
  }
  return { rootPath, files };
}

// ── Main page ─────────────────────────────────────────────────────────

export function CompanyImport() {
  const {
    selectedCompanyId,
    selectedCompany,
    setSelectedCompanyId,
  } = useCompany();
  const { setBreadcrumbs } = useBreadcrumbs();
  const { pushToast } = useToast();
  const queryClient = useQueryClient();
  const packageInputRef = useRef<HTMLInputElement | null>(null);

  // Source state
  const [sourceMode, setSourceMode] = useState<"github" | "url" | "local">("github");
  const [importUrl, setImportUrl] = useState("");
  const [localPackage, setLocalPackage] = useState<{
    rootPath: string | null;
    files: Record<string, string>;
  } | null>(null);

  // Target state
  const [targetMode, setTargetMode] = useState<"existing" | "new">("existing");
  const [collisionStrategy, setCollisionStrategy] =
    useState<CompanyPortabilityCollisionStrategy>("rename");
  const [newCompanyName, setNewCompanyName] = useState("");

  // Preview state
  const [importPreview, setImportPreview] =
    useState<CompanyPortabilityPreviewResult | null>(null);
  const [selectedFile, setSelectedFile] = useState<string | null>(null);
  const [expandedDirs, setExpandedDirs] = useState<Set<string>>(new Set());
  const [checkedFiles, setCheckedFiles] = useState<Set<string>>(new Set());

  useEffect(() => {
    setBreadcrumbs([
      { label: "Org Chart", href: "/org" },
      { label: "Import" },
    ]);
  }, [setBreadcrumbs]);

  function buildSource(): CompanyPortabilitySource | null {
    if (sourceMode === "local") {
      if (!localPackage) return null;
      return { type: "inline", rootPath: localPackage.rootPath, files: localPackage.files };
    }
    const url = importUrl.trim();
    if (!url) return null;
    if (sourceMode === "github") return { type: "github", url };
    return { type: "url", url };
  }

  // Preview mutation
  const previewMutation = useMutation({
    mutationFn: () => {
      const source = buildSource();
      if (!source) throw new Error("No source configured.");
      return companiesApi.importPreview({
        source,
        include: { company: true, agents: true, projects: true, issues: true },
        target:
          targetMode === "new"
            ? { mode: "new_company", newCompanyName: newCompanyName || null }
            : { mode: "existing_company", companyId: selectedCompanyId! },
        collisionStrategy,
      });
    },
    onSuccess: (result) => {
      setImportPreview(result);
      // Check all files by default
      const allFiles = new Set(Object.keys(result.files));
      setCheckedFiles(allFiles);
      // Expand top-level dirs + all ancestor dirs of files with conflicts (update action)
      const am = buildActionMap(result);
      const tree = buildFileTree(result.files, am);
      const dirsToExpand = new Set<string>();
      for (const node of tree) {
        if (node.kind === "dir") dirsToExpand.add(node.path);
      }
      // Auto-expand directories containing conflicting files so they're visible
      for (const [filePath, action] of am) {
        if (action === "update") {
          const segments = filePath.split("/").filter(Boolean);
          let current = "";
          for (let i = 0; i < segments.length - 1; i++) {
            current = current ? `${current}/${segments[i]}` : segments[i];
            dirsToExpand.add(current);
          }
        }
      }
      setExpandedDirs(dirsToExpand);
      // Select first file
      const firstFile = Object.keys(result.files)[0];
      if (firstFile) setSelectedFile(firstFile);
    },
    onError: (err) => {
      pushToast({
        tone: "error",
        title: "Preview failed",
        body: err instanceof Error ? err.message : "Failed to preview import.",
      });
    },
  });

  // Apply mutation
  const importMutation = useMutation({
    mutationFn: () => {
      const source = buildSource();
      if (!source) throw new Error("No source configured.");
      return companiesApi.importBundle({
        source,
        include: { company: true, agents: true, projects: true, issues: true },
        target:
          targetMode === "new"
            ? { mode: "new_company", newCompanyName: newCompanyName || null }
            : { mode: "existing_company", companyId: selectedCompanyId! },
        collisionStrategy,
      });
    },
    onSuccess: async (result) => {
      await queryClient.invalidateQueries({ queryKey: queryKeys.companies.all });
      if (result.company.action === "created") {
        setSelectedCompanyId(result.company.id);
      }
      pushToast({
        tone: "success",
        title: "Import complete",
        body: `${result.company.name}: ${result.agents.length} agent${result.agents.length === 1 ? "" : "s"} processed.`,
      });
      // Reset
      setImportPreview(null);
      setLocalPackage(null);
      setImportUrl("");
    },
    onError: (err) => {
      pushToast({
        tone: "error",
        title: "Import failed",
        body: err instanceof Error ? err.message : "Failed to apply import.",
      });
    },
  });

  async function handleChooseLocalPackage(e: ChangeEvent<HTMLInputElement>) {
    const fileList = e.target.files;
    if (!fileList || fileList.length === 0) return;
    try {
      const pkg = await readLocalPackageSelection(fileList);
      setLocalPackage(pkg);
      setImportPreview(null);
    } catch (err) {
      pushToast({
        tone: "error",
        title: "Package read failed",
        body: err instanceof Error ? err.message : "Failed to read folder.",
      });
    }
  }

  const actionMap = useMemo(
    () => (importPreview ? buildActionMap(importPreview) : new Map<string, string>()),
    [importPreview],
  );

  const tree = useMemo(
    () => (importPreview ? buildFileTree(importPreview.files, actionMap) : []),
    [importPreview, actionMap],
  );

  const totalFiles = useMemo(() => countFiles(tree), [tree]);
  const selectedCount = checkedFiles.size;

  function handleToggleDir(path: string) {
    setExpandedDirs((prev) => {
      const next = new Set(prev);
      if (next.has(path)) next.delete(path);
      else next.add(path);
      return next;
    });
  }

  function handleToggleCheck(path: string, kind: "file" | "dir") {
    if (!importPreview) return;
    setCheckedFiles((prev) => {
      const next = new Set(prev);
      if (kind === "file") {
        if (next.has(path)) next.delete(path);
        else next.add(path);
      } else {
        const findNode = (nodes: FileTreeNode[], target: string): FileTreeNode | null => {
          for (const n of nodes) {
            if (n.path === target) return n;
            const found = findNode(n.children, target);
            if (found) return found;
          }
          return null;
        };
        const dirNode = findNode(tree, path);
        if (dirNode) {
          const childFiles = collectAllPaths(dirNode.children, "file");
          for (const child of dirNode.children) {
            if (child.kind === "file") childFiles.add(child.path);
          }
          const allChecked = [...childFiles].every((p) => next.has(p));
          for (const f of childFiles) {
            if (allChecked) next.delete(f);
            else next.add(f);
          }
        }
      }
      return next;
    });
  }

  const hasSource =
    sourceMode === "local" ? !!localPackage : importUrl.trim().length > 0;
  const hasErrors = importPreview ? importPreview.errors.length > 0 : false;

  const previewContent = selectedFile && importPreview
    ? (importPreview.files[selectedFile] ?? null)
    : null;
  const selectedAction = selectedFile ? (actionMap.get(selectedFile) ?? null) : null;

  if (!selectedCompanyId) {
    return <EmptyState icon={Download} message="Select a company to import into." />;
  }

  return (
    <div>
      {/* Source form section */}
      <div className="border-b border-border px-5 py-5 space-y-4">
        <div>
          <h2 className="text-base font-semibold">Import source</h2>
          <p className="text-xs text-muted-foreground mt-1">
            Choose a GitHub repo, direct URL, or local folder to import from.
          </p>
        </div>

        <div className="grid gap-2 md:grid-cols-3">
          {(
            [
              { key: "github", icon: Github, label: "GitHub repo" },
              { key: "url", icon: Link2, label: "Direct URL" },
              { key: "local", icon: Upload, label: "Local folder" },
            ] as const
          ).map(({ key, icon: Icon, label }) => (
            <button
              key={key}
              type="button"
              className={cn(
                "rounded-md border px-3 py-2 text-left text-sm transition-colors",
                sourceMode === key
                  ? "border-foreground bg-accent"
                  : "border-border hover:bg-accent/50",
              )}
              onClick={() => setSourceMode(key)}
            >
              <div className="flex items-center gap-2">
                <Icon className="h-4 w-4" />
                {label}
              </div>
            </button>
          ))}
        </div>

        {sourceMode === "local" ? (
          <div className="rounded-md border border-dashed border-border px-3 py-3">
            <input
              ref={packageInputRef}
              type="file"
              multiple
              className="hidden"
              // @ts-expect-error webkitdirectory is supported by Chromium-based browsers
              webkitdirectory=""
              onChange={handleChooseLocalPackage}
            />
            <div className="flex flex-wrap items-center gap-2">
              <Button
                size="sm"
                variant="outline"
                onClick={() => packageInputRef.current?.click()}
              >
                Choose folder
              </Button>
              {localPackage && (
                <span className="text-xs text-muted-foreground">
                  {localPackage.rootPath ?? "package"} with{" "}
                  {Object.keys(localPackage.files).length} file
                  {Object.keys(localPackage.files).length === 1 ? "" : "s"}
                </span>
              )}
            </div>
            {!localPackage && (
              <p className="mt-2 text-xs text-muted-foreground">
                Select a folder that contains COMPANY.md and any referenced AGENTS.md files.
              </p>
            )}
          </div>
        ) : (
          <Field
            label={sourceMode === "github" ? "GitHub URL" : "Package URL"}
            hint={
              sourceMode === "github"
                ? "Repo tree path or blob URL to COMPANY.md (e.g. github.com/owner/repo/tree/main/company)."
                : "Point directly at COMPANY.md or a directory that contains it."
            }
          >
            <input
              className="w-full rounded-md border border-border bg-transparent px-2.5 py-1.5 text-sm outline-none"
              type="text"
              value={importUrl}
              placeholder={
                sourceMode === "github"
                  ? "https://github.com/owner/repo/tree/main/company"
                  : "https://example.com/company/COMPANY.md"
              }
              onChange={(e) => {
                setImportUrl(e.target.value);
                setImportPreview(null);
              }}
            />
          </Field>
        )}

        <div className={cn("grid gap-3", targetMode === "existing" ? "md:grid-cols-2" : "md:grid-cols-1")}>
          <Field label="Target" hint="Import into this company or create a new one.">
            <select
              className="w-full rounded-md border border-border bg-transparent px-2.5 py-1.5 text-sm outline-none"
              value={targetMode}
              onChange={(e) => {
                setTargetMode(e.target.value as "existing" | "new");
                setImportPreview(null);
              }}
            >
              <option value="existing">
                Existing company: {selectedCompany?.name}
              </option>
              <option value="new">Create new company</option>
            </select>
          </Field>
          {targetMode === "existing" && (
            <Field
              label="Default collision strategy"
              hint="Controls what happens when imported slugs already exist."
            >
              <select
                className="w-full rounded-md border border-border bg-transparent px-2.5 py-1.5 text-sm outline-none"
                value={collisionStrategy}
                onChange={(e) => {
                  setCollisionStrategy(e.target.value as CompanyPortabilityCollisionStrategy);
                  setImportPreview(null);
                }}
              >
                <option value="rename">Rename imported agents</option>
                <option value="skip">Skip existing agents</option>
                <option value="replace">Replace existing agents</option>
              </select>
            </Field>
          )}
        </div>

        {targetMode === "new" && (
          <Field
            label="New company name"
            hint="Optional override. Leave blank to use the package name."
          >
            <input
              className="w-full rounded-md border border-border bg-transparent px-2.5 py-1.5 text-sm outline-none"
              type="text"
              value={newCompanyName}
              onChange={(e) => setNewCompanyName(e.target.value)}
              placeholder="Imported Company"
            />
          </Field>
        )}

        <div className="flex items-center gap-2">
          <Button
            size="sm"
            variant="outline"
            onClick={() => previewMutation.mutate()}
            disabled={previewMutation.isPending || !hasSource}
          >
            {previewMutation.isPending ? "Previewing..." : "Preview import"}
          </Button>
        </div>
      </div>

      {/* Preview results */}
      {importPreview && (
        <>
          {/* Sticky import action bar */}
          <div className="sticky top-0 z-10 border-b border-border bg-background px-5 py-3">
            <div className="flex flex-wrap items-center justify-between gap-3">
              <div className="flex items-center gap-4 text-sm">
                <span className="font-medium">
                  Import preview
                </span>
                <span className="text-muted-foreground">
                  {selectedCount} / {totalFiles} file{totalFiles === 1 ? "" : "s"} selected
                </span>
                {importPreview.warnings.length > 0 && (
                  <span className="text-amber-500">
                    {importPreview.warnings.length} warning{importPreview.warnings.length === 1 ? "" : "s"}
                  </span>
                )}
                {importPreview.errors.length > 0 && (
                  <span className="text-destructive">
                    {importPreview.errors.length} error{importPreview.errors.length === 1 ? "" : "s"}
                  </span>
                )}
              </div>
              <Button
                size="sm"
                onClick={() => importMutation.mutate()}
                disabled={importMutation.isPending || hasErrors || selectedCount === 0}
              >
                <Download className="mr-1.5 h-3.5 w-3.5" />
                {importMutation.isPending
                  ? "Importing..."
                  : `Import ${selectedCount} file${selectedCount === 1 ? "" : "s"}`}
              </Button>
            </div>
          </div>

          {/* Warnings */}
          {importPreview.warnings.length > 0 && (
            <div className="mx-5 mt-3 rounded-md border border-amber-500/30 bg-amber-500/5 px-4 py-3">
              {importPreview.warnings.map((w) => (
                <div key={w} className="text-xs text-amber-500">{w}</div>
              ))}
            </div>
          )}

          {/* Errors */}
          {importPreview.errors.length > 0 && (
            <div className="mx-5 mt-3 rounded-md border border-destructive/30 bg-destructive/5 px-4 py-3">
              {importPreview.errors.map((e) => (
                <div key={e} className="text-xs text-destructive">{e}</div>
              ))}
            </div>
          )}

          {/* Two-column layout */}
          <div className="grid h-[calc(100vh-16rem)] gap-0 xl:grid-cols-[19rem_minmax(0,1fr)]">
            <aside className="flex flex-col border-r border-border overflow-hidden">
              <div className="border-b border-border px-4 py-3 shrink-0">
                <h2 className="text-base font-semibold">Package files</h2>
              </div>
              <div className="flex-1 overflow-y-auto">
                <PackageFileTree
                  nodes={tree}
                  selectedFile={selectedFile}
                  expandedDirs={expandedDirs}
                  checkedFiles={checkedFiles}
                  onToggleDir={handleToggleDir}
                  onSelectFile={setSelectedFile}
                  onToggleCheck={handleToggleCheck}
                  renderFileExtra={renderImportFileExtra}
                  fileRowClassName={importFileRowClassName}
                />
              </div>
            </aside>
            <div className="min-w-0 overflow-y-auto pl-6">
              <ImportPreviewPane
                selectedFile={selectedFile}
                content={previewContent}
                action={selectedAction}
              />
            </div>
          </div>
        </>
      )}
    </div>
  );
}