import { TRPCError } from "@trpc/server";
import { z } from "zod";
import { and, desc, eq, isNull, ne, isNotNull } from "drizzle-orm";
import {
  workspaces,
  workspaceMembers,
  users,
  objects,
} from "@tasks/database/schema";
import { router, protectedProcedure, workspaceProcedure } from "@/server/trpc";
import { findWorkspaceByHandle } from "@/server/lib/resolve-workspace";
import { recordAudit } from "@/server/lib/audit";

const slugSchema = z
  .string()
  .min(2)
  .max(60)
  .regex(/^[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/, "Slug must be lowercase, alphanumeric, hyphen-separated");

function makeSlug(name: string): string {
  return (
    name
      .trim()
      .toLowerCase()
      .replace(/[^a-z0-9]+/g, "-")
      .replace(/^-+|-+$/g, "")
      .slice(0, 60) || "workspace"
  );
}

export const workspacesRouter = router({
  /**
   * Resolve a UUID-or-slug handle to a workspace the caller can see. Used by
   * the app shell to redirect / hydrate the workspace switcher.
   */
  resolve: protectedProcedure
    .input(z.object({ handle: z.string().min(1) }))
    .query(async ({ ctx, input }) => {
      const ws = await findWorkspaceByHandle(input.handle, ctx.db);
      if (!ws) {
        throw new TRPCError({ code: "NOT_FOUND", message: "Workspace not found" });
      }

      const userId = ctx.session.user.id;
      const [membership] = await ctx.db
        .select({ role: workspaceMembers.role })
        .from(workspaceMembers)
        .where(
          and(
            eq(workspaceMembers.workspaceId, ws.id),
            eq(workspaceMembers.userId, userId),
          ),
        )
        .limit(1);

      const [owner] = await ctx.db
        .select({ ownerUserId: workspaces.ownerUserId })
        .from(workspaces)
        .where(eq(workspaces.id, ws.id))
        .limit(1);

      if (!membership && owner?.ownerUserId !== userId) {
        throw new TRPCError({ code: "FORBIDDEN" });
      }

      return ws;
    }),

  /**
   * Create a new workspace owned by the caller. Auto-mints a slug from `name`
   * unless one is provided. Caller is added as the owner+initial member.
   */
  create: protectedProcedure
    .input(
      z.object({
        name: z.string().min(1).max(200),
        slug: slugSchema.optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      const userId = ctx.session.user.id;
      let slug = input.slug ?? makeSlug(input.name);

      const [collision] = await ctx.db
        .select({ id: workspaces.id })
        .from(workspaces)
        .where(eq(workspaces.slug, slug))
        .limit(1);
      if (collision) {
        if (input.slug) {
          throw new TRPCError({ code: "CONFLICT", message: "Slug already in use" });
        }
        slug = `${slug}-${Math.random().toString(36).slice(2, 8)}`;
      }

      const [ws] = await ctx.db
        .insert(workspaces)
        .values({
          name: input.name,
          slug,
          ownerUserId: userId,
        })
        .returning();

      await ctx.db.insert(workspaceMembers).values({
        workspaceId: ws.id,
        userId,
        role: "owner",
      });

      await recordAudit(ctx.db, {
        workspaceId: ws.id,
        actorUserId: userId,
        action: "workspace.create",
        targetType: "workspace",
        targetId: ws.id,
        metadata: { name: ws.name, slug: ws.slug },
      });

      return ws;
    }),

  /** All workspaces the caller owns or is a member of, owned-first then alpha. */
  listForUser: protectedProcedure.query(async ({ ctx }) => {
    const userId = ctx.session.user.id;

    const owned = await ctx.db
      .select({
        id: workspaces.id,
        slug: workspaces.slug,
        name: workspaces.name,
        role: workspaceMembers.role,
        archivedAt: workspaces.archivedAt,
      })
      .from(workspaces)
      .leftJoin(
        workspaceMembers,
        and(
          eq(workspaceMembers.workspaceId, workspaces.id),
          eq(workspaceMembers.userId, userId),
        ),
      )
      .where(
        and(eq(workspaces.ownerUserId, userId), isNull(workspaces.archivedAt)),
      )
      .orderBy(workspaces.name);

    const memberOnly = await ctx.db
      .select({
        id: workspaces.id,
        slug: workspaces.slug,
        name: workspaces.name,
        role: workspaceMembers.role,
        archivedAt: workspaces.archivedAt,
      })
      .from(workspaceMembers)
      .innerJoin(workspaces, eq(workspaceMembers.workspaceId, workspaces.id))
      .where(
        and(
          eq(workspaceMembers.userId, userId),
          ne(workspaces.ownerUserId, userId),
          isNull(workspaces.archivedAt),
        ),
      )
      .orderBy(workspaces.name);

    return [...owned, ...memberOnly].map((row) => ({
      id: row.id,
      slug: row.slug,
      name: row.name,
      role: row.role ?? "owner",
      archivedAt: row.archivedAt,
    }));
  }),

  /** Members of a workspace the caller can see. */
  listMembers: workspaceProcedure.query(async ({ ctx }) => {
    return ctx.db
      .select({
        id: users.id,
        name: users.name,
        email: users.email,
        avatarUrl: users.avatarUrl,
        role: workspaceMembers.role,
      })
      .from(workspaceMembers)
      .innerJoin(users, eq(workspaceMembers.userId, users.id))
      .where(eq(workspaceMembers.workspaceId, ctx.workspace.id));
  }),

  /**
   * Update workspace metadata (name and/or slug). Slug renames are validated
   * for uniqueness; the caller must be the workspace owner.
   */
  update: workspaceProcedure
    .input(
      z.object({
        name: z.string().min(1).max(200).optional(),
        slug: slugSchema.optional(),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      if (ctx.workspace.role !== "owner") {
        throw new TRPCError({ code: "FORBIDDEN", message: "Only the owner can rename the workspace" });
      }

      if (input.slug && input.slug !== ctx.workspace.slug) {
        const [collision] = await ctx.db
          .select({ id: workspaces.id })
          .from(workspaces)
          .where(eq(workspaces.slug, input.slug))
          .limit(1);
        if (collision) {
          throw new TRPCError({ code: "CONFLICT", message: "Slug already in use" });
        }
      }

      const [updated] = await ctx.db
        .update(workspaces)
        .set({
          ...(input.name ? { name: input.name } : {}),
          ...(input.slug ? { slug: input.slug } : {}),
          updatedAt: new Date(),
        })
        .where(eq(workspaces.id, ctx.workspace.id))
        .returning();

      await recordAudit(ctx.db, {
        workspaceId: ctx.workspace.id,
        actorUserId: ctx.session.user.id,
        action: "workspace.update",
        targetType: "workspace",
        targetId: ctx.workspace.id,
        metadata: {
          ...(input.name ? { name: { before: ctx.workspace.name, after: input.name } } : {}),
          ...(input.slug ? { slug: { before: ctx.workspace.slug, after: input.slug } } : {}),
        },
      });

      return updated;
    }),

  /**
   * Change a member's role. Admin/owner only. Cannot demote the last owner
   * (the workspace would lose the ability to manage members).
   */
  updateMemberRole: workspaceProcedure
    .input(
      z.object({
        userId: z.string().uuid(),
        role: z.enum(["owner", "admin", "member"]),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      if (ctx.workspace.role !== "owner" && ctx.workspace.role !== "admin") {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Only owners and admins can change member roles.",
        });
      }
      if (input.userId === ctx.session.user.id && input.role !== ctx.workspace.role) {
        throw new TRPCError({
          code: "BAD_REQUEST",
          message: "You can't change your own role. Ask another owner or admin.",
        });
      }

      const [target] = await ctx.db
        .select({ role: workspaceMembers.role })
        .from(workspaceMembers)
        .where(
          and(
            eq(workspaceMembers.workspaceId, ctx.workspace.id),
            eq(workspaceMembers.userId, input.userId),
          ),
        )
        .limit(1);
      if (!target) {
        throw new TRPCError({ code: "NOT_FOUND", message: "Member not found." });
      }

      // Last-owner guard: demoting the only owner-role member to admin/member
      // would leave the workspace ownerless at the membership layer (even
      // though `workspaces.owner_user_id` still points at them — see the
      // ADR-pragmatic decision in Task-multi-email-identity convoy discussion).
      if (target.role === "owner" && input.role !== "owner") {
        const ownerCount = await ctx.db
          .select({ id: workspaceMembers.id })
          .from(workspaceMembers)
          .where(
            and(
              eq(workspaceMembers.workspaceId, ctx.workspace.id),
              eq(workspaceMembers.role, "owner"),
            ),
          );
        if (ownerCount.length <= 1) {
          throw new TRPCError({
            code: "BAD_REQUEST",
            message: "Can't demote the only owner. Promote someone else first.",
          });
        }
      }

      // Only owners can promote anyone to owner; admins can move people
      // between admin/member but cannot create another owner.
      if (input.role === "owner" && ctx.workspace.role !== "owner") {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Only an owner can promote someone to owner.",
        });
      }

      await ctx.db
        .update(workspaceMembers)
        .set({ role: input.role })
        .where(
          and(
            eq(workspaceMembers.workspaceId, ctx.workspace.id),
            eq(workspaceMembers.userId, input.userId),
          ),
        );

      await recordAudit(ctx.db, {
        workspaceId: ctx.workspace.id,
        actorUserId: ctx.session.user.id,
        action: "member.role_change",
        targetType: "workspace_member",
        targetId: input.userId,
        metadata: { role: { before: target.role, after: input.role } },
      });

      return { ok: true as const };
    }),

  /**
   * Remove a member from the workspace. Admin/owner only. Cannot remove the
   * last owner (same rationale as the demote guard above). Members can
   * remove themselves — that's the "leave workspace" affordance.
   */
  removeMember: workspaceProcedure
    .input(z.object({ userId: z.string().uuid() }))
    .mutation(async ({ ctx, input }) => {
      const isSelf = input.userId === ctx.session.user.id;
      const callerCanManage =
        ctx.workspace.role === "owner" || ctx.workspace.role === "admin";
      if (!isSelf && !callerCanManage) {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Only owners and admins can remove other members.",
        });
      }

      const [target] = await ctx.db
        .select({ role: workspaceMembers.role })
        .from(workspaceMembers)
        .where(
          and(
            eq(workspaceMembers.workspaceId, ctx.workspace.id),
            eq(workspaceMembers.userId, input.userId),
          ),
        )
        .limit(1);
      if (!target) {
        throw new TRPCError({ code: "NOT_FOUND", message: "Member not found." });
      }

      if (target.role === "owner") {
        const ownerCount = await ctx.db
          .select({ id: workspaceMembers.id })
          .from(workspaceMembers)
          .where(
            and(
              eq(workspaceMembers.workspaceId, ctx.workspace.id),
              eq(workspaceMembers.role, "owner"),
            ),
          );
        if (ownerCount.length <= 1) {
          throw new TRPCError({
            code: "BAD_REQUEST",
            message:
              "Can't remove the only owner. Promote someone else to owner first.",
          });
        }
      }

      // Admins cannot remove owners (only owners can de-owner an owner via
      // updateMemberRole -> removeMember, in that order).
      if (target.role === "owner" && ctx.workspace.role !== "owner" && !isSelf) {
        throw new TRPCError({
          code: "FORBIDDEN",
          message: "Only an owner can remove another owner.",
        });
      }

      await ctx.db
        .delete(workspaceMembers)
        .where(
          and(
            eq(workspaceMembers.workspaceId, ctx.workspace.id),
            eq(workspaceMembers.userId, input.userId),
          ),
        );

      await recordAudit(ctx.db, {
        workspaceId: ctx.workspace.id,
        actorUserId: ctx.session.user.id,
        action: isSelf ? "member.leave" : "member.remove",
        targetType: "workspace_member",
        targetId: input.userId,
        metadata: { previous_role: target.role, self: isSelf },
      });

      return { ok: true as const };
    }),

  /**
   * Owner-only soft archive. Stamps `archived_at` on the workspace row AND
   * cascades to every active `objects` row in the workspace inside the same
   * transaction — so a partial cascade (workspace archived, some objects
   * still active) is not a state we can land in.
   *
   * `markdown_backlog_items` is intentionally NOT cascaded here. Those rows
   * are sourced from disk by the file-watcher importer; if a workspace is
   * archived, restoring it just re-syncs from disk and the importer will
   * re-establish the rows. Filed as a follow-up if/when that assumption
   * stops holding.
   */
  archive: workspaceProcedure.mutation(async ({ ctx }) => {
    if (ctx.workspace.role !== "owner") {
      throw new TRPCError({ code: "FORBIDDEN" });
    }

    const archivedAt = new Date();
    const result = await ctx.db.transaction(async (tx) => {
      const [updated] = await tx
        .update(workspaces)
        .set({ archivedAt })
        .where(eq(workspaces.id, ctx.workspace.id))
        .returning();

      const archivedObjects = await tx
        .update(objects)
        .set({ archivedAt, updatedAt: archivedAt })
        .where(
          and(eq(objects.workspaceId, ctx.workspace.id), isNull(objects.archivedAt)),
        )
        .returning({ id: objects.id });

      return { updated, cascadeCount: archivedObjects.length };
    });

    await recordAudit(ctx.db, {
      workspaceId: ctx.workspace.id,
      actorUserId: ctx.session.user.id,
      action: "workspace.archive",
      targetType: "workspace",
      targetId: ctx.workspace.id,
      metadata: { cascaded_objects: result.cascadeCount },
    });

    return result.updated;
  }),

  /**
   * Owner-only restore. Inverse of `archive`: clears `archived_at` on the
   * workspace and on every object that was archived as part of the same
   * cascade. We can't tell "was this object archived by the workspace
   * cascade vs. archived independently?" without recording per-object
   * archive provenance, so for v1 we restore EVERY archived object in the
   * workspace. That's the conservative-recovery behavior; if it surprises
   * anyone we'll add provenance tracking later.
   */
  restore: workspaceProcedure.mutation(async ({ ctx }) => {
    if (ctx.workspace.role !== "owner") {
      throw new TRPCError({ code: "FORBIDDEN" });
    }
    const [current] = await ctx.db
      .select({ archivedAt: workspaces.archivedAt })
      .from(workspaces)
      .where(eq(workspaces.id, ctx.workspace.id))
      .limit(1);
    if (!current?.archivedAt) {
      throw new TRPCError({
        code: "BAD_REQUEST",
        message: "Workspace is not archived.",
      });
    }

    const result = await ctx.db.transaction(async (tx) => {
      const [updated] = await tx
        .update(workspaces)
        .set({ archivedAt: null })
        .where(eq(workspaces.id, ctx.workspace.id))
        .returning();

      const restoredObjects = await tx
        .update(objects)
        .set({ archivedAt: null, updatedAt: new Date() })
        .where(
          and(
            eq(objects.workspaceId, ctx.workspace.id),
            isNotNull(objects.archivedAt),
          ),
        )
        .returning({ id: objects.id });

      return { updated, cascadeCount: restoredObjects.length };
    });

    await recordAudit(ctx.db, {
      workspaceId: ctx.workspace.id,
      actorUserId: ctx.session.user.id,
      action: "workspace.restore",
      targetType: "workspace",
      targetId: ctx.workspace.id,
      metadata: { restored_objects: result.cascadeCount },
    });

    return result.updated;
  }),
});