'use node';

import { getAuthUserId } from '@convex-dev/auth/server';
import { ConvexError, v } from 'convex/values';

import type { Doc, Id } from './_generated/dataModel';
import type { ActionCtx } from './_generated/server';
import type { GitHubCompareSummary } from './githubClient';
import { internal } from './_generated/api';
import { action, internalAction } from './_generated/server';
import {
  compareAcrossForkNetwork,
  getInstallationOctokit,
  getRepository,
  getSpoonInstallationId,
  listPullRequests,
  syncForkBranch,
} from './githubClient';

const getRequiredUserId = async (ctx: ActionCtx) => {
  const userId = await getAuthUserId(ctx);
  if (!userId) throw new ConvexError('Not authenticated.');
  return userId;
};

const toStatus = (upstreamAheadBy: number, forkAheadBy: number) => {
  if (upstreamAheadBy === 0 && forkAheadBy === 0) return 'up_to_date' as const;
  if (upstreamAheadBy > 0 && forkAheadBy === 0) return 'behind' as const;
  if (upstreamAheadBy === 0 && forkAheadBy > 0) return 'ahead' as const;
  if (upstreamAheadBy > 0 && forkAheadBy > 0) return 'diverged' as const;
  return 'unknown' as const;
};

const getLastCommitAt = (compare: GitHubCompareSummary) =>
  compare.commits[compare.commits.length - 1]?.committedAt;

const ensureForkMetadata = (spoon: Doc<'spoons'>) => {
  if (!spoon.forkOwner || !spoon.forkRepo) {
    throw new ConvexError('Fork metadata is required before GitHub refresh.');
  }
  return {
    forkOwner: spoon.forkOwner,
    forkRepo: spoon.forkRepo,
    forkBranch: spoon.forkDefaultBranch ?? spoon.upstreamDefaultBranch,
  };
};

const refreshOwnedSpoon = async (
  ctx: ActionCtx,
  ownerId: Id<'users'>,
  spoonId: Id<'spoons'>,
  kind: 'manual_check' | 'scheduled_check' = 'manual_check',
): Promise<{
  success: boolean;
  status: ReturnType<typeof toStatus>;
  upstreamAheadBy: number;
  forkAheadBy: number;
}> => {
  const spoon: Doc<'spoons'> = await ctx.runQuery(
    internal.spoons.getOwnedForAction,
    {
      spoonId,
      ownerId,
    },
  );
  if (spoon.provider !== 'github') {
    throw new ConvexError(
      'GitHub refresh is only available for GitHub Spoons.',
    );
  }
  const connection = await ctx.runQuery(internal.github.getConnectionForUser, {
    userId: ownerId,
  });
  const installationId = getSpoonInstallationId(spoon, connection);
  const { forkOwner, forkRepo, forkBranch } = ensureForkMetadata(spoon);
  const syncRunId = await ctx.runMutation(internal.syncRuns.createInternal, {
    spoonId,
    ownerId,
    kind,
    status: 'running',
    summary: 'Refreshing GitHub repository state.',
  });

  await ctx.runMutation(internal.spoons.patchSyncFields, {
    spoonId,
    syncStatus: 'checking',
    lastSyncRunId: syncRunId,
    lastGithubRefreshAt: Date.now(),
  });

  try {
    const octokit = getInstallationOctokit(installationId);
    const [upstreamRepo, forkRepoData] = await Promise.all([
      getRepository(octokit, spoon.upstreamOwner, spoon.upstreamRepo),
      getRepository(octokit, forkOwner, forkRepo),
    ]);
    const upstreamBranch =
      spoon.upstreamDefaultBranch || upstreamRepo.default_branch;
    const resolvedForkBranch = forkBranch || forkRepoData.default_branch;
    const [upstreamCompare, forkCompare, forkPulls, upstreamPulls]: [
      GitHubCompareSummary,
      GitHubCompareSummary,
      Awaited<ReturnType<typeof listPullRequests>>,
      Awaited<ReturnType<typeof listPullRequests>>,
    ] = await Promise.all([
      compareAcrossForkNetwork(octokit, {
        owner: spoon.upstreamOwner,
        repo: spoon.upstreamRepo,
        baseOwner: forkOwner,
        baseBranch: resolvedForkBranch,
        headOwner: spoon.upstreamOwner,
        headBranch: upstreamBranch,
      }),
      compareAcrossForkNetwork(octokit, {
        owner: spoon.upstreamOwner,
        repo: spoon.upstreamRepo,
        baseOwner: spoon.upstreamOwner,
        baseBranch: upstreamBranch,
        headOwner: forkOwner,
        headBranch: resolvedForkBranch,
      }),
      listPullRequests(octokit, { owner: forkOwner, repo: forkRepo }),
      listPullRequests(octokit, {
        owner: spoon.upstreamOwner,
        repo: spoon.upstreamRepo,
        head: `${forkOwner}:${resolvedForkBranch}`,
      }),
    ]);
    const status = toStatus(upstreamCompare.aheadBy, forkCompare.aheadBy);
    const openForkPullRequestCount = forkPulls.filter(
      (pull) => pull.state === 'open',
    ).length;
    const openUpstreamPullRequestCount = upstreamPulls.filter(
      (pull) => pull.state === 'open',
    ).length;
    const now = Date.now();

    await Promise.all([
      ctx.runMutation(internal.spoonState.upsert, {
        spoonId,
        ownerId,
        upstreamFullName: upstreamRepo.full_name,
        forkFullName: forkRepoData.full_name,
        upstreamDefaultBranch: upstreamRepo.default_branch,
        forkDefaultBranch: forkRepoData.default_branch,
        upstreamHeadSha: upstreamCompare.headSha,
        forkHeadSha: forkCompare.headSha,
        mergeBaseSha: upstreamCompare.mergeBaseSha ?? forkCompare.mergeBaseSha,
        upstreamAheadBy: upstreamCompare.aheadBy,
        forkAheadBy: forkCompare.aheadBy,
        status,
        openForkPullRequestCount,
        openUpstreamPullRequestCount,
        lastCommitAt:
          getLastCommitAt(upstreamCompare) ?? getLastCommitAt(forkCompare),
        rawCompareUrl: upstreamCompare.htmlUrl,
      }),
      ctx.runMutation(internal.spoonCommits.replaceForSpoon, {
        spoonId,
        ownerId,
        side: 'upstream',
        commits: upstreamCompare.commits,
      }),
      ctx.runMutation(internal.spoonCommits.replaceForSpoon, {
        spoonId,
        ownerId,
        side: 'fork',
        commits: forkCompare.commits,
      }),
      ctx.runMutation(internal.spoonPullRequests.replaceForSpoon, {
        spoonId,
        ownerId,
        scope: 'fork',
        pullRequests: forkPulls,
      }),
      ctx.runMutation(internal.spoonPullRequests.replaceForSpoon, {
        spoonId,
        ownerId,
        scope: 'from_fork_to_upstream',
        pullRequests: upstreamPulls,
      }),
    ]);

    await ctx.runMutation(internal.spoons.patchSyncFields, {
      spoonId,
      syncStatus: status,
      upstreamAheadBy: upstreamCompare.aheadBy,
      forkAheadBy: forkCompare.aheadBy,
      lastMergeBaseCommit:
        upstreamCompare.mergeBaseSha ?? forkCompare.mergeBaseSha,
      lastUpstreamCommit: upstreamCompare.headSha,
      lastForkCommit: forkCompare.headSha,
      lastGithubRefreshAt: now,
      lastSuccessfulRefreshAt: now,
      lastCheckedAt: now,
      lastError: '',
    });
    await ctx.runMutation(internal.syncRuns.patchInternal, {
      syncRunId,
      status: status === 'diverged' ? 'needs_review' : 'clean',
      summary: `GitHub refresh complete: ${upstreamCompare.aheadBy} upstream commit(s), ${forkCompare.aheadBy} fork-only commit(s).`,
    });
    return {
      success: true,
      status,
      upstreamAheadBy: upstreamCompare.aheadBy,
      forkAheadBy: forkCompare.aheadBy,
    };
  } catch (error) {
    const message = error instanceof Error ? error.message : String(error);
    await Promise.all([
      ctx.runMutation(internal.spoons.patchSyncFields, {
        spoonId,
        syncStatus: 'error',
        lastGithubRefreshAt: Date.now(),
        lastCheckedAt: Date.now(),
        lastError: message,
      }),
      ctx.runMutation(internal.syncRuns.patchInternal, {
        syncRunId,
        status: 'failed',
        error: message,
      }),
    ]);
    throw new ConvexError(message);
  }
};

export const refreshSpoonGithubState = action({
  args: { spoonId: v.id('spoons') },
  handler: async (
    ctx,
    { spoonId },
  ): Promise<{
    success: boolean;
    status: ReturnType<typeof toStatus>;
    upstreamAheadBy: number;
    forkAheadBy: number;
  }> => {
    const ownerId = await getRequiredUserId(ctx);
    return await refreshOwnedSpoon(ctx, ownerId, spoonId);
  },
});

export const syncForkWithUpstream = action({
  args: { spoonId: v.id('spoons') },
  handler: async (
    ctx,
    { spoonId },
  ): Promise<{
    success: boolean;
    status: ReturnType<typeof toStatus>;
    upstreamAheadBy: number;
    forkAheadBy: number;
  }> => {
    const ownerId = await getRequiredUserId(ctx);
    const spoon: Doc<'spoons'> = await ctx.runQuery(
      internal.spoons.getOwnedForAction,
      {
        spoonId,
        ownerId,
      },
    );
    const state = await ctx.runQuery(internal.spoonState.getInternal, {
      spoonId,
      ownerId,
    });
    if (state?.status !== 'behind' || state.forkAheadBy !== 0) {
      throw new ConvexError(
        'Sync is only available for behind, non-diverged forks.',
      );
    }
    const connection = await ctx.runQuery(
      internal.github.getConnectionForUser,
      {
        userId: ownerId,
      },
    );
    const installationId = getSpoonInstallationId(spoon, connection);
    const { forkOwner, forkRepo, forkBranch } = ensureForkMetadata(spoon);
    const syncRunId = await ctx.runMutation(internal.syncRuns.createInternal, {
      spoonId,
      ownerId,
      kind: 'merge_attempt',
      status: 'running',
      summary: 'Syncing fork branch with upstream.',
    });
    try {
      const octokit = getInstallationOctokit(installationId);
      await syncForkBranch(octokit, {
        forkOwner,
        forkRepo,
        branch: forkBranch,
      });
      await ctx.runMutation(internal.syncRuns.patchInternal, {
        syncRunId,
        status: 'merged',
        summary: 'GitHub fork sync completed.',
      });
      return await refreshOwnedSpoon(ctx, ownerId, spoonId, 'manual_check');
    } catch (error) {
      const message = error instanceof Error ? error.message : String(error);
      const conflict = message.toLowerCase().includes('conflict');
      await ctx.runMutation(internal.syncRuns.patchInternal, {
        syncRunId,
        status: conflict ? 'conflict' : 'failed',
        error: message,
      });
      await ctx.runMutation(internal.spoons.patchSyncFields, {
        spoonId,
        syncStatus: conflict ? 'conflict' : 'error',
        lastError: message,
      });
      throw new ConvexError(message);
    }
  },
});

export const refreshDueSpoons = internalAction({
  args: { limit: v.optional(v.number()) },
  handler: async (
    ctx,
    { limit },
  ): Promise<
    (
      | {
          success: boolean;
          status: ReturnType<typeof toStatus>;
          upstreamAheadBy: number;
          forkAheadBy: number;
        }
      | { success: false; spoonId: Id<'spoons'>; error: string }
    )[]
  > => {
    const due: { spoonId: Id<'spoons'>; ownerId: Id<'users'> }[] =
      await ctx.runQuery(internal.spoonSettings.listRefreshDue, {
        limit: limit ?? 10,
      });
    const results: (
      | {
          success: boolean;
          status: ReturnType<typeof toStatus>;
          upstreamAheadBy: number;
          forkAheadBy: number;
        }
      | { success: false; spoonId: Id<'spoons'>; error: string }
    )[] = [];
    for (const item of due) {
      try {
        results.push(
          await refreshOwnedSpoon(
            ctx,
            item.ownerId,
            item.spoonId,
            'scheduled_check',
          ),
        );
      } catch (error) {
        results.push({
          success: false,
          spoonId: item.spoonId,
          error: error instanceof Error ? error.message : String(error),
        });
      }
    }
    return results;
  },
});