import { useEffect, useMemo } from "react";
import { useSessionGitStatus, useSessionGitStatusByRepo } from "./use-session-git-status";
import { useCumulativeDiff } from "./use-cumulative-diff";
import { useActiveTaskPR } from "@/hooks/domains/github/use-task-pr";
import { usePRDiff } from "@/hooks/domains/github/use-pr-diff";
import { normalizeDiffContent } from "@/components/review/types";
import { createDebugLogger } from "@/lib/debug/log";
import type { ReviewFile } from "@/components/review/types";
import type { PRDiffFile } from "@/lib/types/github";

const debug = createDebugLogger("review:sources");

export type ReviewSource = "uncommitted" | "committed" | "pr";

export type SourceCounts = Record<ReviewSource, number>;

type UncommittedFile = {
  diff?: string;
  diff_skip_reason?: ReviewFile["diff_skip_reason"];
  status?: string;
  additions?: number;
  deletions?: number;
  staged?: boolean;
};

type CumulativeFile = {
  diff?: string;
  status?: string;
  additions?: number;
  deletions?: number;
  repository_name?: string;
};

function addUncommittedFiles(
  fileMap: Map<string, ReviewFile>,
  files: Record<string, UncommittedFile>,
  repositoryName?: string,
) {
  for (const [path, file] of Object.entries(files)) {
    const diff = file.diff ? normalizeDiffContent(file.diff) : "";
    const skipReason = file.diff_skip_reason;
    if (!diff && !skipReason) continue;
    const key = repositoryName ? `${repositoryName}:${path}` : path;
    fileMap.set(key, {
      path,
      diff,
      status: file.status ?? "modified",
      additions: file.additions ?? 0,
      deletions: file.deletions ?? 0,
      staged: file.staged ?? false,
      source: "uncommitted",
      diff_skip_reason: skipReason,
      repository_name: repositoryName,
    });
  }
}

function addCumulativeFiles(
  fileMap: Map<string, ReviewFile>,
  files: Record<string, CumulativeFile>,
  uncommittedPaths: Set<string>,
) {
  for (const [path, file] of Object.entries(files)) {
    const key = file.repository_name ? `${file.repository_name}:${path}` : path;
    const hasRepoUnawareCollision = key !== path && fileMap.has(path);
    if (fileMap.has(key) || uncommittedPaths.has(key) || hasRepoUnawareCollision) continue;
    const diff = file.diff ? normalizeDiffContent(file.diff) : "";
    if (!diff) continue;
    fileMap.set(key, {
      path,
      diff,
      status: file.status || "modified",
      additions: file.additions ?? 0,
      deletions: file.deletions ?? 0,
      staged: false,
      source: "committed",
      repository_name: file.repository_name,
    });
  }
}

function prFileStatus(status: string): "added" | "deleted" | "modified" {
  if (status === "added") return "added";
  if (status === "removed") return "deleted";
  return "modified";
}

function addPRFiles(
  fileMap: Map<string, ReviewFile>,
  files: PRDiffFile[],
  uncommittedPaths: Set<string>,
  repoName?: string,
) {
  for (const file of files) {
    const key = repoName ? `${repoName}:${file.filename}` : file.filename;
    const hasRepoUnawareCollision = key !== file.filename && fileMap.has(file.filename);
    if (fileMap.has(key) || uncommittedPaths.has(key) || hasRepoUnawareCollision) continue;
    const diff = file.patch ? normalizeDiffContent(file.patch) : "";
    if (!diff) continue;
    fileMap.set(key, {
      path: file.filename,
      diff,
      status: prFileStatus(file.status),
      additions: file.additions ?? 0,
      deletions: file.deletions ?? 0,
      staged: false,
      source: "pr",
      repository_name: repoName,
    });
  }
}

function collectPathsFromFiles(
  paths: Set<string>,
  files: Record<string, UncommittedFile>,
  repositoryName?: string,
): void {
  for (const [path, file] of Object.entries(files)) {
    const diff = file.diff ? normalizeDiffContent(file.diff) : "";
    if (diff || file.diff_skip_reason) {
      // Always add bare path (for deduping repo-unaware sources like cumulative
      // diffs that may not carry repository_name).
      paths.add(path);
      // Also add composite key (for repo-aware dedup when sources carry repo info).
      if (repositoryName) paths.add(`${repositoryName}:${path}`);
    }
  }
}

function collectUncommittedPaths(
  statusByRepo: BuildReviewSourcesInput["statusByRepo"],
  gitStatus: BuildReviewSourcesInput["gitStatus"],
): Set<string> {
  const paths = new Set<string>();
  if (statusByRepo && statusByRepo.length > 0) {
    for (const { repository_name, status } of statusByRepo) {
      if (status?.files)
        collectPathsFromFiles(
          paths,
          status.files as Record<string, UncommittedFile>,
          repository_name || undefined,
        );
    }
  } else if (gitStatus?.files) {
    collectPathsFromFiles(paths, gitStatus.files as Record<string, UncommittedFile>);
  }
  return paths;
}

export type BuildReviewSourcesInput = {
  gitStatus: { files?: Record<string, UncommittedFile> } | undefined;
  statusByRepo:
    | Array<{ repository_name: string; status: { files?: Record<string, UncommittedFile> } }>
    | undefined;
  cumulativeDiff: { files?: Record<string, CumulativeFile> } | null;
  prDiffFiles: PRDiffFile[] | undefined;
  /** Repository name for the primary PR — used to composite-key PR files so
   *  same-named files in different repos are not incorrectly deduped. */
  prRepoName?: string;
};

export type BuildReviewSourcesResult = {
  allFiles: ReviewFile[];
  sourceCounts: SourceCounts;
};

/**
 * Pure helper that merges the three diff sources into one sorted, deduped
 * list and computes per-source counts. Uncommitted files write first under
 * composite `repo:path` keys (multi-repo) or simple `path` keys (single-repo).
 * Committed and PR files write next under simple `path` keys but skip any
 * path that already appears in the uncommitted set — preserving dedup
 * priority (uncommitted > committed > PR) across the key-shape mismatch.
 */
export function buildReviewSources(input: BuildReviewSourcesInput): BuildReviewSourcesResult {
  const { gitStatus, statusByRepo, cumulativeDiff, prDiffFiles, prRepoName } = input;
  const fileMap = new Map<string, ReviewFile>();

  const uncommittedPaths = collectUncommittedPaths(statusByRepo, gitStatus);

  if (statusByRepo && statusByRepo.length > 0) {
    for (const { repository_name, status } of statusByRepo) {
      if (status?.files) {
        addUncommittedFiles(
          fileMap,
          status.files as Record<string, UncommittedFile>,
          repository_name || undefined,
        );
      }
    }
  } else if (gitStatus?.files) {
    addUncommittedFiles(fileMap, gitStatus.files as Record<string, UncommittedFile>);
  }

  if (cumulativeDiff?.files) addCumulativeFiles(fileMap, cumulativeDiff.files, uncommittedPaths);

  if (prDiffFiles && prDiffFiles.length > 0)
    addPRFiles(fileMap, prDiffFiles, uncommittedPaths, prRepoName);

  const allFiles = Array.from(fileMap.values()).sort((a, b) => {
    const repoCmp = (a.repository_name ?? "").localeCompare(b.repository_name ?? "");
    if (repoCmp !== 0) return repoCmp;
    return a.path.localeCompare(b.path);
  });

  const sourceCounts: SourceCounts = { uncommitted: 0, committed: 0, pr: 0 };
  for (const f of allFiles) sourceCounts[f.source]++;

  return { allFiles, sourceCounts };
}

export type UseReviewSourcesResult = {
  allFiles: ReviewFile[];
  sourceCounts: SourceCounts;
  hasPR: boolean;
  cumulativeLoading: boolean;
  prDiffLoading: boolean;
  /** Raw single-repo gitStatus (kept for `useAutoCloseWhenEmpty` consumers). */
  gitStatus: ReturnType<typeof useSessionGitStatus>;
  /**
   * Raw PR diff files as ReviewFile[], NOT deduplicated with uncommitted/committed.
   * Use when displaying the PR-specific diff for a file (e.g. clicking a PR file row),
   * where the same file may also have local changes that would win deduplication in allFiles.
   * NOTE: Only covers the primary PR (single-repo tasks). Multi-PR support is Bug 2.
   */
  rawPRFiles: ReviewFile[];
};

/**
 * Multi-source merge hook. Aggregates uncommitted / committed / PR diffs
 * into one sorted ReviewFile[] tagged with `.source`. Shared by
 * `TaskChangesPanel` (diff viewer) and `MobileDiffSheet` (source tab bar).
 *
 * Returns counts per source so consumers can render tab badges without
 * re-running the merge.
 */
export function useReviewSources(sessionId: string | null | undefined): UseReviewSourcesResult {
  const gitStatus = useSessionGitStatus(sessionId ?? null);
  const statusByRepo = useSessionGitStatusByRepo(sessionId ?? null);
  const { diff: cumulativeDiff, loading: cumulativeLoading } = useCumulativeDiff(sessionId ?? null);
  const pr = useActiveTaskPR();
  const { files: prDiffFiles, loading: prDiffLoading } = usePRDiff(
    pr?.owner ?? null,
    pr?.repo ?? null,
    pr?.pr_number ?? null,
  );

  const { allFiles, sourceCounts } = useMemo(
    () =>
      buildReviewSources({
        gitStatus,
        statusByRepo,
        cumulativeDiff: cumulativeDiff as { files?: Record<string, CumulativeFile> } | null,
        prDiffFiles: prDiffFiles.length > 0 ? prDiffFiles : undefined,
        prRepoName: pr?.repo || undefined,
      }),
    [gitStatus, statusByRepo, cumulativeDiff, prDiffFiles, pr?.repo],
  );

  const rawPRFiles = useMemo(() => {
    if (!prDiffFiles || prDiffFiles.length === 0) return [] as ReviewFile[];
    const fileMap = new Map<string, ReviewFile>();
    addPRFiles(fileMap, prDiffFiles, new Set(), pr?.repo || undefined);
    return Array.from(fileMap.values());
  }, [prDiffFiles, pr?.repo]);

  // Keep `hasPR` keyed on the existence of a TaskPR row, not on whether the
  // PR diff files have loaded yet — avoids the tab bar reflowing the moment
  // the GitHub PR diff hydrates.
  const hasPR = !!pr;

  useEffect(() => {
    if (!sessionId) return;
    debug("merged", {
      sessionId,
      total: allFiles.length,
      uncommitted: sourceCounts.uncommitted,
      committed: sourceCounts.committed,
      pr: sourceCounts.pr,
      hasPR,
      hasCumulativeDiff: !!cumulativeDiff,
      cumulativeLoading,
      prDiffLoading,
      prRepo: pr?.repo ?? null,
      prNumber: pr?.pr_number ?? null,
    });
  }, [
    sessionId,
    allFiles.length,
    sourceCounts.uncommitted,
    sourceCounts.committed,
    sourceCounts.pr,
    hasPR,
    cumulativeDiff,
    cumulativeLoading,
    prDiffLoading,
    pr?.repo,
    pr?.pr_number,
  ]);

  return {
    allFiles,
    sourceCounts,
    hasPR,
    cumulativeLoading,
    prDiffLoading,
    gitStatus,
    rawPRFiles,
  };
}

export type { CumulativeFile, UncommittedFile };