import * as schema from '@db/schema';

import { TGroupmember, TNewGroupmember } from '@db/types';
import { and, eq, or } from 'drizzle-orm';

import { ROLE } from '@cio/utils/constants';
import { db } from '@db/drizzle';

/**
 * Gets all course members (people) for a course
 * Returns members with their profile information
 * @param courseId Course ID
 * @returns Array of course members with profile data
 */
export async function getCourseMembers(courseId: string): Promise<
  Array<
    TGroupmember & {
      profile: {
        id: string;
        fullname: string | null;
        username: string | null;
        avatarUrl: string | null;
        email: string | null;
      } | null;
    }
  >
> {
  try {
    const result = await db
      .select({
        member: schema.groupmember,
        profile: {
          id: schema.profile.id,
          fullname: schema.profile.fullname,
          username: schema.profile.username,
          avatarUrl: schema.profile.avatarUrl,
          email: schema.profile.email
        }
      })
      .from(schema.groupmember)
      .innerJoin(schema.course, eq(schema.course.groupId, schema.groupmember.groupId))
      .leftJoin(schema.profile, eq(schema.groupmember.profileId, schema.profile.id))
      .where(eq(schema.course.id, courseId));

    return result.map((row) => ({
      ...row.member,
      profile: row.profile || null
    }));
  } catch (error) {
    console.error('getCourseMembers error:', error);
    throw new Error(`Failed to get course members: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Gets a course member by ID
 * @param courseId Course ID
 * @param memberId Member ID
 * @returns Course member with profile data or null if not found
 */
export async function getCourseMember(
  courseId: string,
  memberId: string
): Promise<
  | (TGroupmember & {
      profile: {
        id: string;
        fullname: string | null;
        username: string | null;
        avatarUrl: string | null;
        email: string | null;
      } | null;
    })
  | null
> {
  try {
    const result = await db
      .select({
        member: schema.groupmember,
        profile: {
          id: schema.profile.id,
          fullname: schema.profile.fullname,
          username: schema.profile.username,
          avatarUrl: schema.profile.avatarUrl,
          email: schema.profile.email
        }
      })
      .from(schema.groupmember)
      .innerJoin(schema.course, eq(schema.course.groupId, schema.groupmember.groupId))
      .leftJoin(schema.profile, eq(schema.groupmember.profileId, schema.profile.id))
      .where(and(eq(schema.course.id, courseId), eq(schema.groupmember.id, memberId)))
      .limit(1);

    if (result.length === 0) {
      return null;
    }

    return {
      ...result[0].member,
      profile: result[0].profile || null
    };
  } catch (error) {
    console.error('getCourseMember error:', error);
    throw new Error(`Failed to get course member: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Gets the group ID for a course
 * @param courseId Course ID
 * @returns Group ID or null if not found
 */
export async function getCourseGroupId(courseId: string): Promise<string | null> {
  try {
    const result = await db
      .select({ groupId: schema.course.groupId })
      .from(schema.course)
      .where(eq(schema.course.id, courseId))
      .limit(1);

    return result.length > 0 ? result[0].groupId : null;
  } catch (error) {
    console.error('getCourseGroupId error:', error);
    throw new Error(`Failed to get course group ID: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Gets teachers (ADMIN or TUTOR role) for a course
 * @param options.courseId Course ID (optional if groupId provided)
 * @param options.groupId Group ID (optional if courseId provided)
 * @param options.limit Optional limit (default: no limit, returns all)
 * @returns Array of teachers with profile data
 */
type TeacherProfile = {
  id: string;
  email: string | null;
  fullname: string | null;
  username: string | null;
  avatarUrl: string | null;
};

export async function getCourseTeachers(options: {
  courseId?: string;
  groupId?: string;
  limit?: number;
}): Promise<Array<TeacherProfile>> {
  const { courseId, groupId, limit } = options;

  if (!courseId && !groupId) {
    throw new Error('Either courseId or groupId must be provided');
  }

  const profileSelect = {
    id: schema.profile.id,
    email: schema.profile.email,
    fullname: schema.profile.fullname,
    username: schema.profile.username,
    avatarUrl: schema.profile.avatarUrl
  };

  const isTeacherRole = or(eq(schema.groupmember.roleId, ROLE.ADMIN), eq(schema.groupmember.roleId, ROLE.TUTOR));

  const baseQuery = db
    .select(profileSelect)
    .from(schema.groupmember)
    .innerJoin(schema.profile, eq(schema.groupmember.profileId, schema.profile.id));

  const query = courseId
    ? baseQuery
        .innerJoin(schema.course, eq(schema.course.groupId, schema.groupmember.groupId))
        .where(and(eq(schema.course.id, courseId), isTeacherRole))
    : baseQuery.where(and(eq(schema.groupmember.groupId, groupId!), isTeacherRole));

  const result = await (limit ? query.limit(limit) : query);

  return result;
}

/**
 * Adds a course member (person) to a course
 * @param courseId Course ID
 * @param memberData Member data (profileId, roleId, email)
 * @returns Created member
 */
export async function addCourseMember(
  courseId: string,
  memberData: { profileId?: string; roleId: number; email?: string }
): Promise<TGroupmember> {
  try {
    const groupId = await getCourseGroupId(courseId);
    if (!groupId) {
      throw new Error('Course group not found');
    }

    const [newMember] = await db
      .insert(schema.groupmember)
      .values({
        groupId,
        profileId: memberData.profileId,
        roleId: memberData.roleId,
        email: memberData.email
      })
      .returning();

    if (!newMember) {
      throw new Error('Failed to create course member');
    }

    return newMember;
  } catch (error) {
    console.error('addCourseMember error:', error);
    throw new Error(`Failed to add course member: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Updates a course member
 * @param courseId Course ID
 * @param memberId Member ID
 * @param data Partial member data to update
 * @returns Updated member
 */
export async function updateCourseMember(
  courseId: string,
  memberId: string,
  data: Partial<TGroupmember>
): Promise<TGroupmember | null> {
  try {
    // Verify member belongs to course
    const member = await getCourseMember(courseId, memberId);
    if (!member) {
      return null;
    }

    const [updated] = await db
      .update(schema.groupmember)
      .set(data)
      .where(eq(schema.groupmember.id, memberId))
      .returning();

    return updated || null;
  } catch (error) {
    console.error('updateCourseMember error:', error);
    throw new Error(`Failed to update course member: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Deletes a course member
 * @param courseId Course ID
 * @param memberId Member ID
 * @returns Deleted member or null if not found
 */
export async function deleteCourseMember(courseId: string, memberId: string): Promise<TGroupmember | null> {
  try {
    // Verify member belongs to course
    const member = await getCourseMember(courseId, memberId);
    if (!member) {
      return null;
    }

    const [deleted] = await db.delete(schema.groupmember).where(eq(schema.groupmember.id, memberId)).returning();

    return deleted || null;
  } catch (error) {
    console.error('deleteCourseMember error:', error);
    throw new Error(`Failed to delete course member: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Gets profile data by group member ID
 * @param groupMemberId Group member ID
 * @returns Profile data or null if not found
 */
export async function getProfileByGroupMemberId(groupMemberId: string): Promise<{
  id: string;
  fullname: string | null;
  username: string | null;
  avatarUrl: string | null;
  email: string | null;
} | null> {
  try {
    const result = await db
      .select({
        id: schema.profile.id,
        fullname: schema.profile.fullname,
        username: schema.profile.username,
        avatarUrl: schema.profile.avatarUrl,
        email: schema.profile.email
      })
      .from(schema.groupmember)
      .innerJoin(schema.profile, eq(schema.groupmember.profileId, schema.profile.id))
      .where(eq(schema.groupmember.id, groupMemberId))
      .limit(1);

    if (result.length === 0) {
      return null;
    }

    return result[0];
  } catch (error) {
    console.error('getProfileByGroupMemberId error:', error);
    throw new Error(
      `Failed to get profile by group member ID "${groupMemberId}": ${error instanceof Error ? error.message : 'Unknown error'}`
    );
  }
}

/**
 * Sets when the learner first met certification threshold for this course membership.
 */
export async function setMemberCertificateEarned(memberId: string, earnedAt: string): Promise<TGroupmember | null> {
  try {
    const [updated] = await db
      .update(schema.groupmember)
      .set({ certificateEarnedAt: earnedAt })
      .where(eq(schema.groupmember.id, memberId))
      .returning();
    return updated ?? null;
  } catch (error) {
    console.error('setMemberCertificateEarned error:', error);
    throw new Error(`Failed to set certificate earned: ${error instanceof Error ? error.message : 'Unknown error'}`);
  }
}

/**
 * Records that the certification congratulations email was sent.
 */
export async function setMemberCertificationEmailSent(memberId: string, sentAt: string): Promise<TGroupmember | null> {
  try {
    const [updated] = await db
      .update(schema.groupmember)
      .set({ certificationEmailSentAt: sentAt })
      .where(eq(schema.groupmember.id, memberId))
      .returning();
    return updated ?? null;
  } catch (error) {
    console.error('setMemberCertificationEmailSent error:', error);
    throw new Error(
      `Failed to set certification email sent: ${error instanceof Error ? error.message : 'Unknown error'}`
    );
  }
}