import { env } from "@code/env/convex";
import {
  CREDENTIAL_FRESHNESS_MS,
  isCredentialFresh,
} from "@code/primitives/git-provider";
import { makeFunctionReference } from "convex/server";
import { ConvexError, v } from "convex/values";

import type { Doc, Id } from "./_generated/dataModel";
import {
  action,
  internalMutation,
  internalQuery,
  query,
} from "./_generated/server";
import { requireCurrentOrganization } from "./authz";

interface VerifyResult {
  readonly lastError?: string;
  readonly state: "active" | "reauth-required" | "unavailable";
}

const decodeBase64url = (value: string): Uint8Array<ArrayBuffer> => {
  const padded = value
    .replaceAll("-", "+")
    .replaceAll("_", "/")
    .padEnd(Math.ceil(value.length / 4) * 4, "=");
  const decoded = atob(padded);
  const bytes = new Uint8Array(decoded.length);
  for (let index = 0; index < decoded.length; index += 1) {
    const codePoint = decoded.codePointAt(index);
    if (codePoint === undefined) {
      throw new ConvexError("Invalid credential encoding");
    }
    bytes[index] = codePoint;
  }
  return bytes;
};

const credentialEncryptionKey = async (): Promise<CryptoKey> => {
  if (!env.GIT_CREDENTIAL_ENCRYPTION_KEY) {
    throw new ConvexError("Git credential encryption is not configured");
  }
  const bytes = decodeBase64url(env.GIT_CREDENTIAL_ENCRYPTION_KEY);
  if (bytes.byteLength !== 32) {
    throw new ConvexError("Git credential encryption key must be 32 bytes");
  }
  return await crypto.subtle.importKey("raw", bytes, "AES-GCM", false, [
    "decrypt",
  ]);
};

const decryptCredential = async (
  credentialCiphertext: string,
  credentialIv: string
): Promise<string> => {
  const decrypted = await crypto.subtle.decrypt(
    {
      iv: decodeBase64url(credentialIv),
      name: "AES-GCM",
    },
    await credentialEncryptionKey(),
    decodeBase64url(credentialCiphertext)
  );
  return new TextDecoder().decode(decrypted);
};

const verifyGiteaCredential = async (
  serverUrl: string,
  token: string
): Promise<VerifyResult> => {
  try {
    const response = await fetch(
      `${serverUrl.replace(/\/+$/u, "")}/api/v1/user`,
      { headers: { authorization: `token ${token}` } }
    );
    if (response.status === 401 || response.status === 403) {
      return { lastError: "Token rejected", state: "reauth-required" };
    }
    if (!response.ok) {
      return {
        lastError: `Provider returned ${response.status}`,
        state: "unavailable",
      };
    }
    return { state: "active" };
  } catch (error) {
    return {
      lastError: error instanceof Error ? error.message : "Unreachable",
      state: "unavailable",
    };
  }
};

const verifyGithubCredential = async (token: string): Promise<VerifyResult> => {
  try {
    const response = await fetch("https://api.github.com/user", {
      headers: {
        accept: "application/vnd.github+json",
        authorization: `Bearer ${token}`,
      },
    });
    if (response.status === 401 || response.status === 403) {
      return { lastError: "Token rejected", state: "reauth-required" };
    }
    if (!response.ok) {
      return {
        lastError: `Provider returned ${response.status}`,
        state: "unavailable",
      };
    }
    return { state: "active" };
  } catch (error) {
    return {
      lastError: error instanceof Error ? error.message : "Unreachable",
      state: "unavailable",
    };
  }
};

export const verifyCredential = async (
  connection: Doc<"gitConnections">
): Promise<VerifyResult> => {
  const credential = await decryptCredential(
    connection.credentialCiphertext,
    connection.credentialIv
  );
  return connection.provider === "gitea"
    ? verifyGiteaCredential(connection.serverUrl, credential)
    : verifyGithubCredential(credential);
};

export const updateConnectionState = internalMutation({
  args: {
    connectionId: v.id("gitConnections"),
    lastError: v.optional(v.string()),
    state: v.union(
      v.literal("active"),
      v.literal("reauth-required"),
      v.literal("unavailable")
    ),
  },
  handler: async (ctx, args) => {
    const timestamp = Date.now();
    const patch: Record<string, unknown> = {
      lastError: args.lastError,
      state: args.state,
      updatedAt: timestamp,
    };
    if (args.state === "active") {
      patch.lastError = undefined;
      patch.lastVerifiedAt = timestamp;
      patch.reauthRequiredAt = undefined;
    } else if (args.state === "reauth-required") {
      patch.reauthRequiredAt = timestamp;
    }
    await ctx.db.patch(args.connectionId, patch);
  },
});


const getConnectionRef = makeFunctionReference<
  "query",
  { connectionId: Id<"gitConnections"> },
  Doc<"gitConnections"> | null
>("gitConnectionHealth:getConnection");

const getStaleConnectionsRef = makeFunctionReference<
  "query",
  Record<string, never>,
  { connectionId: Id<"gitConnections"> }[]
>("gitConnectionHealth:getStaleConnections");
const resolvePersonalOrgRef = makeFunctionReference<
  "query",
  { userId: string },
  Id<"organizations"> | null
>("gitConnections:resolvePersonalOrg");

const updateConnectionStateRef = makeFunctionReference<
  "mutation",
  {
    connectionId: Id<"gitConnections">;
    lastError?: string;
    state: "active" | "reauth-required" | "unavailable";
  },
  null
>("gitConnectionHealth:updateConnectionState");

export const getConnectionForOwner = internalQuery({
  args: { connectionId: v.id("gitConnections") },
  handler: async (ctx, args) => {
    const { organizationId } = await requireCurrentOrganization(ctx);
    const connection = await ctx.db.get(args.connectionId);
    if (!connection || connection.organizationId !== organizationId) {
      return null;
    }
    return connection;
  },
});

export const getConnection = internalQuery({
  args: { connectionId: v.id("gitConnections") },
  handler: async (ctx, args) => await ctx.db.get(args.connectionId),
});

export const resolvePersonalOrg = internalQuery({
  args: { userId: v.string() },
  handler: async (ctx, args): Promise<Id<"organizations"> | null> => {
    const org = await ctx.db
      .query("organizations")
      .withIndex("by_createdBy_and_kind", (q) =>
        q.eq("createdBy", args.userId).eq("kind", "personal")
      )
      .unique();
    return org?._id ?? null;
  },
});

export const getStaleConnections = internalQuery({
  args: {},
  handler: async (ctx) => {
    const now = Date.now();
    const cutoff = now - CREDENTIAL_FRESHNESS_MS;
    const all = await ctx.db.query("gitConnections").collect();
    return all
      .filter(
        (conn) =>
          (conn.state === "active" &&
            (conn.lastVerifiedAt === undefined ||
              conn.lastVerifiedAt < cutoff)) ||
          conn.state === "reauth-required" ||
          conn.state === undefined
      )
      .map((conn) => ({ connectionId: conn._id }));
  },
});

export const verify = action({
  args: { connectionId: v.id("gitConnections") },
  handler: async (ctx, args) => {
    // Resolve identity in the action; sub-queries via runQuery don't inherit it.
    const identity = await ctx.auth.getUserIdentity();
    if (!identity) {
      throw new ConvexError("Authentication required");
    }
    const organizationId = await ctx.runQuery(resolvePersonalOrgRef, {
      userId: identity.tokenIdentifier,
    });
    if (!organizationId) {
      throw new ConvexError("Organization not found");
    }
    const connection = await ctx.runQuery(getConnectionRef, {
      connectionId: args.connectionId,
    });
    if (!connection || connection.organizationId !== organizationId) {
      throw new ConvexError("Git connection not found");
    }
    const result = await verifyCredential(connection);
    await ctx.runMutation(updateConnectionStateRef, {
      connectionId: args.connectionId,
      lastError: result.lastError,
      state: result.state,
    });
    return result;
  },
});

export const isFresh = query({
  args: { connectionId: v.id("gitConnections") },
  handler: async (ctx, args): Promise<boolean> => {
    const { organizationId } = await requireCurrentOrganization(ctx);
    const connection = await ctx.db.get(args.connectionId);
    if (!connection || connection.organizationId !== organizationId) {
      throw new ConvexError("Git connection not found");
    }
    return isCredentialFresh(connection.lastVerifiedAt, Date.now());
  },
});

export const reconcileStaleConnections = action({
  args: {},
  handler: async (ctx) => {
    const stale = await ctx.runQuery(getStaleConnectionsRef, {});
    let checked = 0;
    for (const { connectionId } of stale) {
      const connection = await ctx.runQuery(getConnectionRef, {
        connectionId,
      });
      if (!connection) {
        continue;
      }
      try {
        const result = await verifyCredential(connection);
        await ctx.runMutation(updateConnectionStateRef, {
          connectionId,
          lastError: result.lastError,
          state: result.state,
        });
        checked += 1;
      } catch {
        await ctx.runMutation(updateConnectionStateRef, {
          connectionId,
          lastError: "Verification failed",
          state: "unavailable",
        });
      }
    }
    return { checked };
  },
});


/**
 * Returns the active GitHub connection for an organization (used by the
 * live-repo-search action when no explicit connectionId is supplied).
 */
export const getActiveGithubConnection = internalQuery({
  args: { organizationId: v.id("organizations") },
  handler: async (ctx, args) => {
    const connections = await ctx.db
      .query("gitConnections")
      .withIndex("by_organizationId", (q) =>
        q.eq("organizationId", args.organizationId)
      )
      .filter((q) =>
        q.and(
          q.eq(q.field("provider"), "github"),
          q.or(
            q.eq(q.field("state"), "active"),
            q.eq(q.field("state"), undefined)
          )
        )
      )
      .first();
    return connections ?? null;
  },
});

/**
 * Resolves gitRepositoryIds for a set of external GitHub repository IDs
 * (used by live search to return stable Convex IDs after upserting results).
 */
export const getGithubRepoIdsByExternalIds = internalQuery({
  args: {
    organizationId: v.id("organizations"),
    providerRepositoryIds: v.array(v.string()),
    serverUrl: v.string(),
  },
  handler: async (ctx, args) => {
    const results: { id: string; providerRepositoryId: string }[] = [];
    for (const providerRepositoryId of args.providerRepositoryIds) {
      const existing = await ctx.db
        .query("gitRepositories")
        .withIndex("by_provider_and_serverUrl_and_externalRepositoryId", (q) =>
          q
            .eq("provider", "github")
            .eq("serverUrl", args.serverUrl)
            .eq("providerRepositoryId", providerRepositoryId)
        )
        .unique();
      if (existing) {
        results.push({
          id: String(existing._id),
          providerRepositoryId,
        });
      }
    }
    return results;
  },
});