import type {
  CanvasGenerationDialogState,
  GenerateDialogState,
} from './ImageCanvasEditorTypes';

export const BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS = 200;
export const BACKGROUND_MUSIC_PROMPT_SIMPLIFICATION_MAX_CODE_POINTS =
  BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS * 10;
export const BACKGROUND_MUSIC_PROMPT_GENERATION_MIN_EFFECTIVE_CODE_POINTS = 1;
export const BACKGROUND_MUSIC_PROMPT_COMPLETION_MIN_EFFECTIVE_CODE_POINTS = 2;

const UNICODE_WHITE_SPACE_CODE_POINT = /^\p{White_Space}$/u;
const LEADING_UNICODE_WHITE_SPACE = /^\p{White_Space}+/u;
const TRAILING_UNICODE_WHITE_SPACE = /\p{White_Space}+$/u;
const BACKGROUND_MUSIC_PROMPT_OPERATION_ID_PREFIX =
  'background-music-prompt-operation';

export type BackgroundMusicPromptOperationStatus =
  | 'completing'
  | 'simplifying'
  | 'submitting';

export type BackgroundMusicPromptDialogStatus =
  | 'idle'
  | BackgroundMusicPromptOperationStatus;

export type BackgroundMusicPromptOperation = {
  dialogId: string;
  operationId: string;
  status: BackgroundMusicPromptOperationStatus;
  canonicalPrompt: string;
};

export type BackgroundMusicPromptDialogState = {
  dialogId: string;
  status: BackgroundMusicPromptDialogStatus;
  operationId: string | null;
  undoPromptSnapshot: string | null;
  temporaryPromptSnapshot: string | null;
};

export type BackgroundMusicPromptOperationStartResult = {
  started: boolean;
  reason: 'started' | 'duplicate' | 'ineligible' | 'locked';
  canonicalPrompt: string;
  operation: BackgroundMusicPromptOperation | null;
  state: BackgroundMusicPromptDialogState;
};

export type BackgroundMusicPromptOperationResolution = {
  applied: boolean;
  prompt: string | null;
  state: BackgroundMusicPromptDialogState;
};

export type BackgroundMusicPromptBoundaryResult = {
  applied: boolean;
  prompt: string;
  state: BackgroundMusicPromptDialogState;
};

type InternalBackgroundMusicPromptDialogState =
  BackgroundMusicPromptDialogState & {
    activeCanonicalPrompt: string | null;
  };

export type BackgroundMusicPromptStateModel = ReturnType<
  typeof createBackgroundMusicPromptStateModel
>;

export type BackgroundMusicGenerationDialogState =
  CanvasGenerationDialogState & {
    mode: 'audio-background-music';
  };

/**
 * `GenerateDialogState` 是单一对象类型而不是可判别联合，`mode === 'audio-background-music'`
 * 只窄化属性读取，展开后 `mode` 与可选 `id` 仍是宽类型。助手动作全部按 dialog ID 生效，
 * 所以消费前必须先收窄出带稳定 ID 的 BGM dialog，不能把可选 `id` 直接传下去。
 */
export function toBackgroundMusicGenerationDialog(
  dialog: GenerateDialogState | null,
): BackgroundMusicGenerationDialogState | null {
  if (!dialog || dialog.mode !== 'audio-background-music' || !dialog.id) {
    return null;
  }
  return { ...dialog, id: dialog.id, mode: 'audio-background-music' };
}

export function canonicalizeBackgroundMusicPrompt(prompt: string) {
  return prompt
    .replace(LEADING_UNICODE_WHITE_SPACE, '')
    .replace(TRAILING_UNICODE_WHITE_SPACE, '');
}

export function countPromptCodePoints(prompt: string) {
  return Array.from(canonicalizeBackgroundMusicPrompt(prompt)).length;
}

export function countEffectivePromptCodePoints(prompt: string) {
  let effectiveCodePoints = 0;
  for (const codePoint of canonicalizeBackgroundMusicPrompt(prompt)) {
    if (!UNICODE_WHITE_SPACE_CODE_POINT.test(codePoint)) {
      effectiveCodePoints += 1;
    }
  }
  return effectiveCodePoints;
}

export function canGenerateBackgroundMusicFromPrompt(prompt: string) {
  return (
    countPromptCodePoints(prompt) <= BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS &&
    countEffectivePromptCodePoints(prompt) >=
      BACKGROUND_MUSIC_PROMPT_GENERATION_MIN_EFFECTIVE_CODE_POINTS
  );
}

export function canCompleteBackgroundMusicPrompt(prompt: string) {
  return (
    countPromptCodePoints(prompt) <= BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS &&
    countEffectivePromptCodePoints(prompt) >=
      BACKGROUND_MUSIC_PROMPT_COMPLETION_MIN_EFFECTIVE_CODE_POINTS
  );
}

export function canSimplifyBackgroundMusicPrompt(prompt: string) {
  const codePointCount = countPromptCodePoints(prompt);
  return (
    codePointCount > BACKGROUND_MUSIC_PROMPT_MAX_CODE_POINTS &&
    codePointCount <= BACKGROUND_MUSIC_PROMPT_SIMPLIFICATION_MAX_CODE_POINTS &&
    countEffectivePromptCodePoints(prompt) >=
      BACKGROUND_MUSIC_PROMPT_GENERATION_MIN_EFFECTIVE_CODE_POINTS
  );
}

function createIdleBackgroundMusicPromptDialogState(
  dialogId: string,
): InternalBackgroundMusicPromptDialogState {
  return {
    dialogId,
    status: 'idle',
    operationId: null,
    undoPromptSnapshot: null,
    temporaryPromptSnapshot: null,
    activeCanonicalPrompt: null,
  };
}

function toPublicBackgroundMusicPromptDialogState(
  state: InternalBackgroundMusicPromptDialogState,
): BackgroundMusicPromptDialogState {
  return {
    dialogId: state.dialogId,
    status: state.status,
    operationId: state.operationId,
    undoPromptSnapshot: state.undoPromptSnapshot,
    temporaryPromptSnapshot: state.temporaryPromptSnapshot,
  };
}

function canStartBackgroundMusicPromptOperation(
  status: BackgroundMusicPromptOperationStatus,
  canonicalPrompt: string,
) {
  if (status === 'completing') {
    return canCompleteBackgroundMusicPrompt(canonicalPrompt);
  }
  if (status === 'simplifying') {
    return canSimplifyBackgroundMusicPrompt(canonicalPrompt);
  }
  return canGenerateBackgroundMusicFromPrompt(canonicalPrompt);
}

/**
 * Keeps dialog-scoped Prompt workflow state outside React. All operation claims
 * happen synchronously, so callers can store one model instance in a ref and
 * decide whether to issue a request before their first await.
 */
export function createBackgroundMusicPromptStateModel() {
  const dialogStates = new Map<
    string,
    InternalBackgroundMusicPromptDialogState
  >();
  let operationSequence = 0;

  const readInternalState = (dialogId: string) =>
    dialogStates.get(dialogId) ??
    createIdleBackgroundMusicPromptDialogState(dialogId);

  const saveState = (state: InternalBackgroundMusicPromptDialogState) => {
    dialogStates.set(state.dialogId, state);
    return toPublicBackgroundMusicPromptDialogState(state);
  };

  const getDialogState = (dialogId: string): BackgroundMusicPromptDialogState =>
    toPublicBackgroundMusicPromptDialogState(readInternalState(dialogId));

  const beginOperation = ({
    dialogId,
    status,
    prompt,
  }: {
    dialogId: string;
    status: BackgroundMusicPromptOperationStatus;
    prompt: string;
  }): BackgroundMusicPromptOperationStartResult => {
    const currentState = readInternalState(dialogId);
    const canonicalPrompt = canonicalizeBackgroundMusicPrompt(prompt);

    if (currentState.status === status && currentState.operationId !== null) {
      return {
        started: false,
        reason: 'duplicate',
        canonicalPrompt: currentState.activeCanonicalPrompt ?? canonicalPrompt,
        operation: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    if (currentState.status === 'submitting') {
      return {
        started: false,
        reason: 'locked',
        canonicalPrompt: currentState.activeCanonicalPrompt ?? canonicalPrompt,
        operation: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    if (!canStartBackgroundMusicPromptOperation(status, canonicalPrompt)) {
      return {
        started: false,
        reason: 'ineligible',
        canonicalPrompt,
        operation: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    operationSequence += 1;
    const operation: BackgroundMusicPromptOperation = {
      dialogId,
      operationId: `${BACKGROUND_MUSIC_PROMPT_OPERATION_ID_PREFIX}-${operationSequence}`,
      status,
      canonicalPrompt,
    };
    const isAiOperation = status === 'completing' || status === 'simplifying';
    const nextState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      status,
      operationId: operation.operationId,
      undoPromptSnapshot: isAiOperation
        ? null
        : currentState.undoPromptSnapshot,
      temporaryPromptSnapshot: isAiOperation ? canonicalPrompt : null,
      activeCanonicalPrompt: canonicalPrompt,
    };

    return {
      started: true,
      reason: 'started',
      canonicalPrompt,
      operation,
      state: saveState(nextState),
    };
  };

  const isCurrentOperation = (
    operation: BackgroundMusicPromptOperation,
    state: InternalBackgroundMusicPromptDialogState,
  ) =>
    state.dialogId === operation.dialogId &&
    state.operationId === operation.operationId &&
    state.status === operation.status;

  const resolveAiOperation = (
    operation: BackgroundMusicPromptOperation,
    prompt: string,
  ): BackgroundMusicPromptOperationResolution => {
    const currentState = readInternalState(operation.dialogId);
    if (
      operation.status === 'submitting' ||
      !isCurrentOperation(operation, currentState)
    ) {
      return {
        applied: false,
        prompt: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    const canonicalPrompt = canonicalizeBackgroundMusicPrompt(prompt);
    if (!canGenerateBackgroundMusicFromPrompt(canonicalPrompt)) {
      const failedState: InternalBackgroundMusicPromptDialogState = {
        ...currentState,
        status: 'idle',
        operationId: null,
        undoPromptSnapshot: null,
        temporaryPromptSnapshot: null,
        activeCanonicalPrompt: null,
      };
      return {
        applied: false,
        prompt: null,
        state: saveState(failedState),
      };
    }

    const completedState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      status: 'idle',
      operationId: null,
      undoPromptSnapshot: currentState.temporaryPromptSnapshot,
      temporaryPromptSnapshot: null,
      activeCanonicalPrompt: null,
    };
    return {
      applied: true,
      prompt: canonicalPrompt,
      state: saveState(completedState),
    };
  };

  const rejectOperation = (
    operation: BackgroundMusicPromptOperation,
  ): BackgroundMusicPromptOperationResolution => {
    const currentState = readInternalState(operation.dialogId);
    if (!isCurrentOperation(operation, currentState)) {
      return {
        applied: false,
        prompt: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    const isAiOperation = operation.status !== 'submitting';
    const failedState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      status: 'idle',
      operationId: null,
      undoPromptSnapshot: isAiOperation
        ? null
        : currentState.undoPromptSnapshot,
      temporaryPromptSnapshot: null,
      activeCanonicalPrompt: null,
    };
    return {
      applied: true,
      prompt: currentState.activeCanonicalPrompt,
      state: saveState(failedState),
    };
  };

  const completeSubmittingOperation = (
    operation: BackgroundMusicPromptOperation,
  ): BackgroundMusicPromptOperationResolution => {
    const currentState = readInternalState(operation.dialogId);
    if (
      operation.status !== 'submitting' ||
      !isCurrentOperation(operation, currentState)
    ) {
      return {
        applied: false,
        prompt: null,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    const submittedPrompt =
      currentState.activeCanonicalPrompt ?? operation.canonicalPrompt;
    const completedState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      status: 'idle',
      operationId: null,
      temporaryPromptSnapshot: null,
      activeCanonicalPrompt: null,
    };
    return {
      applied: true,
      prompt: submittedPrompt,
      state: saveState(completedState),
    };
  };

  const preparePreset = (
    dialogId: string,
    prompt: string,
  ): BackgroundMusicPromptBoundaryResult => {
    const currentState = readInternalState(dialogId);
    const canonicalPrompt = canonicalizeBackgroundMusicPrompt(prompt);
    if (currentState.status === 'submitting') {
      return {
        applied: false,
        prompt: currentState.activeCanonicalPrompt ?? canonicalPrompt,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }
    const nextState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      status: 'idle',
      operationId: null,
      undoPromptSnapshot: null,
      temporaryPromptSnapshot: null,
      activeCanonicalPrompt: null,
    };
    return {
      applied: true,
      prompt: canonicalPrompt,
      state: saveState(nextState),
    };
  };

  const swapUndoSnapshot = (
    dialogId: string,
    prompt: string,
  ): BackgroundMusicPromptBoundaryResult => {
    const currentState = readInternalState(dialogId);
    if (
      currentState.status !== 'idle' ||
      currentState.undoPromptSnapshot === null
    ) {
      return {
        applied: false,
        prompt,
        state: toPublicBackgroundMusicPromptDialogState(currentState),
      };
    }

    const canonicalPrompt = canonicalizeBackgroundMusicPrompt(prompt);
    const nextPrompt = currentState.undoPromptSnapshot;
    const nextState: InternalBackgroundMusicPromptDialogState = {
      ...currentState,
      undoPromptSnapshot: canonicalPrompt,
    };
    return {
      applied: true,
      prompt: nextPrompt,
      state: saveState(nextState),
    };
  };

  const closeDialog = (dialogId: string) => {
    dialogStates.delete(dialogId);
  };

  const reset = () => {
    dialogStates.clear();
  };

  return {
    getDialogState,
    beginOperation,
    resolveAiOperation,
    rejectOperation,
    completeSubmittingOperation,
    preparePreset,
    swapUndoSnapshot,
    closeDialog,
    reset,
  };
}