import { and, eq } from "drizzle-orm";
import {
  assertProjectFloorDeleteProjectCommand,
  assertProjectFloorInsertProjectCommand,
  assertProjectRoomDeleteProjectCommand,
  assertProjectRoomInsertProjectCommand,
  createProjectFloorDeleteProjectCommand,
  createProjectFloorInsertProjectCommand,
  createProjectRoomDeleteProjectCommand,
  createProjectRoomInsertProjectCommand,
  projectFloorDeleteCommandType,
  projectFloorInsertCommandType,
  projectRoomDeleteCommandType,
  projectRoomInsertCommandType,
  type ProjectFloorSnapshot,
  type ProjectLocationStructureProjectCommand,
  type ProjectRoomSnapshot,
} from "../../domain/models/project-location-structure-project-command.model.js";
import type {
  ExecuteProjectLocationStructureCommandInput,
  ProjectLocationStructureProjectCommandStore,
} from "../../domain/ports/project-location-structure-project-command.store.js";
import type { AppDatabase } from "../database-context.js";
import { circuitDeviceRows } from "../schema/circuit-device-rows.js";
import { consumers } from "../schema/consumers.js";
import { floors } from "../schema/floors.js";
import { projects } from "../schema/projects.js";
import { rooms } from "../schema/rooms.js";
import { applyProjectHistoryTransition } from "./project-history.persistence.js";
import { appendProjectRevision } from "./project-revision.persistence.js";

export class ProjectLocationStructureProjectCommandRepository
  implements ProjectLocationStructureProjectCommandStore
{
  constructor(private readonly database: AppDatabase) {}

  execute(input: ExecuteProjectLocationStructureCommandInput) {
    return this.database.transaction((tx) => {
      const inverse = this.applyCommand(
        tx,
        input.projectId,
        input.command
      );
      const revision = appendProjectRevision(tx, {
        projectId: input.projectId,
        expectedRevision: input.expectedRevision,
        source: input.source,
        description: input.description,
        actorId: input.actorId,
        forward: input.command,
        inverse,
      });
      applyProjectHistoryTransition(tx, {
        projectId: input.projectId,
        source: input.source,
        recordedChangeSetId: revision.changeSetId,
        targetChangeSetId: input.historyTargetChangeSetId,
      });
      return { revision, inverse };
    });
  }

  private applyCommand(
    database: AppDatabase,
    projectId: string,
    command: ProjectLocationStructureProjectCommand
  ): ProjectLocationStructureProjectCommand {
    switch (command.type) {
      case projectFloorInsertCommandType:
        assertProjectFloorInsertProjectCommand(command);
        return this.insertFloor(
          database,
          projectId,
          command.payload.floor
        );
      case projectFloorDeleteCommandType:
        assertProjectFloorDeleteProjectCommand(command);
        return this.deleteFloor(
          database,
          projectId,
          command.payload.floor
        );
      case projectRoomInsertCommandType:
        assertProjectRoomInsertProjectCommand(command);
        return this.insertRoom(
          database,
          projectId,
          command.payload.room
        );
      case projectRoomDeleteCommandType:
        assertProjectRoomDeleteProjectCommand(command);
        return this.deleteRoom(
          database,
          projectId,
          command.payload.room
        );
    }
  }

  private insertFloor(
    database: AppDatabase,
    projectId: string,
    floor: ProjectFloorSnapshot
  ) {
    this.assertProjectExists(database, projectId);
    if (floor.projectId !== projectId) {
      throw new Error("Project-floor snapshot does not belong to project.");
    }
    const existing = database
      .select({ id: floors.id })
      .from(floors)
      .where(eq(floors.id, floor.id))
      .get();
    if (existing) {
      throw new Error("Project-floor id already exists.");
    }
    database.insert(floors).values(floor).run();
    return createProjectFloorDeleteProjectCommand(floor);
  }

  private deleteFloor(
    database: AppDatabase,
    projectId: string,
    expected: ProjectFloorSnapshot
  ) {
    const persisted = database
      .select()
      .from(floors)
      .where(
        and(
          eq(floors.id, expected.id),
          eq(floors.projectId, projectId)
        )
      )
      .get();
    if (!persisted || !sameRecord(expected, persisted)) {
      throw new Error("Project floor changed before deletion.");
    }
    const referencedRoom = database
      .select({ id: rooms.id })
      .from(rooms)
      .where(eq(rooms.floorId, expected.id))
      .limit(1)
      .get();
    if (referencedRoom) {
      throw new Error(
        "A project floor with assigned rooms cannot be removed by history."
      );
    }
    const deleted = database
      .delete(floors)
      .where(
        and(
          eq(floors.id, expected.id),
          eq(floors.projectId, projectId)
        )
      )
      .run();
    if (deleted.changes !== 1) {
      throw new Error("Project floor could not be deleted.");
    }
    return createProjectFloorInsertProjectCommand(expected);
  }

  private insertRoom(
    database: AppDatabase,
    projectId: string,
    room: ProjectRoomSnapshot
  ) {
    this.assertProjectExists(database, projectId);
    if (room.projectId !== projectId) {
      throw new Error("Project-room snapshot does not belong to project.");
    }
    if (room.floorId) {
      const floor = database
        .select({ id: floors.id })
        .from(floors)
        .where(
          and(
            eq(floors.id, room.floorId),
            eq(floors.projectId, projectId)
          )
        )
        .get();
      if (!floor) {
        throw new Error("Project room references a foreign floor.");
      }
    }
    const existing = database
      .select({ id: rooms.id })
      .from(rooms)
      .where(eq(rooms.id, room.id))
      .get();
    if (existing) {
      throw new Error("Project-room id already exists.");
    }
    database.insert(rooms).values(room).run();
    return createProjectRoomDeleteProjectCommand(room);
  }

  private deleteRoom(
    database: AppDatabase,
    projectId: string,
    expected: ProjectRoomSnapshot
  ) {
    const persisted = database
      .select()
      .from(rooms)
      .where(
        and(
          eq(rooms.id, expected.id),
          eq(rooms.projectId, projectId)
        )
      )
      .get();
    if (!persisted || !sameRecord(expected, persisted)) {
      throw new Error("Project room changed before deletion.");
    }
    const referencedDeviceRow = database
      .select({ id: circuitDeviceRows.id })
      .from(circuitDeviceRows)
      .where(eq(circuitDeviceRows.roomId, expected.id))
      .limit(1)
      .get();
    const referencedLegacyConsumer = database
      .select({ id: consumers.id })
      .from(consumers)
      .where(eq(consumers.roomId, expected.id))
      .limit(1)
      .get();
    if (referencedDeviceRow || referencedLegacyConsumer) {
      throw new Error(
        "A referenced project room cannot be removed by history."
      );
    }
    const deleted = database
      .delete(rooms)
      .where(
        and(
          eq(rooms.id, expected.id),
          eq(rooms.projectId, projectId)
        )
      )
      .run();
    if (deleted.changes !== 1) {
      throw new Error("Project room could not be deleted.");
    }
    return createProjectRoomInsertProjectCommand(expected);
  }

  private assertProjectExists(
    database: AppDatabase,
    projectId: string
  ) {
    const project = database
      .select({ id: projects.id })
      .from(projects)
      .where(eq(projects.id, projectId))
      .get();
    if (!project) {
      throw new Error("Project does not exist.");
    }
  }
}

function sameRecord(
  expected: object,
  actual: object
) {
  const expectedEntries = Object.entries(expected);
  const actualRecord = actual as Record<string, unknown>;
  return (
    expectedEntries.length === Object.keys(actual).length &&
    expectedEntries.every(([key, value]) => actualRecord[key] === value)
  );
}