import {
  detectComposerTrigger as detectComposerTriggerBase,
  type ComposerTrigger,
  type ComposerTriggerKind,
  type ComposerSlashCommand,
} from "@t3tools/shared/composerTrigger";
export {
  replaceTextRange,
  parseStandaloneComposerSlashCommand,
} from "@t3tools/shared/composerTrigger";
export type { ComposerTrigger, ComposerTriggerKind, ComposerSlashCommand };

import { splitPromptIntoComposerSegments } from "./composer-editor-mentions";
import { INLINE_TERMINAL_CONTEXT_PLACEHOLDER } from "./lib/terminalContext";

const isInlineTokenSegment = (
  segment:
    | { type: "text"; text: string }
    | { type: "mention" }
    | { type: "skill" }
    | { type: "terminal-context" },
): boolean => segment.type !== "text";

function clampCursor(text: string, cursor: number): number {
  if (!Number.isFinite(cursor)) return text.length;
  return Math.max(0, Math.min(text.length, Math.floor(cursor)));
}

function isWhitespace(char: string): boolean {
  return (
    char === " " ||
    char === "\n" ||
    char === "\t" ||
    char === "\r" ||
    char === INLINE_TERMINAL_CONTEXT_PLACEHOLDER
  );
}

export function expandCollapsedComposerCursor(text: string, cursorInput: number): number {
  const collapsedCursor = clampCursor(text, cursorInput);
  const segments = splitPromptIntoComposerSegments(text);
  if (segments.length === 0) {
    return collapsedCursor;
  }

  let remaining = collapsedCursor;
  let expandedCursor = 0;

  for (const segment of segments) {
    if (segment.type === "mention") {
      const expandedLength = segment.path.length + 1;
      if (remaining <= 1) {
        return expandedCursor + (remaining === 0 ? 0 : expandedLength);
      }
      remaining -= 1;
      expandedCursor += expandedLength;
      continue;
    }
    if (segment.type === "skill") {
      const expandedLength = segment.name.length + 1;
      if (remaining <= 1) {
        return expandedCursor + (remaining === 0 ? 0 : expandedLength);
      }
      remaining -= 1;
      expandedCursor += expandedLength;
      continue;
    }
    if (segment.type === "terminal-context") {
      if (remaining <= 1) {
        return expandedCursor + remaining;
      }
      remaining -= 1;
      expandedCursor += 1;
      continue;
    }

    const segmentLength = segment.text.length;
    if (remaining <= segmentLength) {
      return expandedCursor + remaining;
    }
    remaining -= segmentLength;
    expandedCursor += segmentLength;
  }

  return expandedCursor;
}

function collapsedSegmentLength(
  segment:
    | { type: "text"; text: string }
    | { type: "mention" }
    | { type: "skill" }
    | { type: "terminal-context" },
): number {
  if (segment.type === "text") {
    return segment.text.length;
  }
  return 1;
}

function clampCollapsedComposerCursorForSegments(
  segments: ReadonlyArray<
    | { type: "text"; text: string }
    | { type: "mention" }
    | { type: "skill" }
    | { type: "terminal-context" }
  >,
  cursorInput: number,
): number {
  const collapsedLength = segments.reduce(
    (total, segment) => total + collapsedSegmentLength(segment),
    0,
  );
  if (!Number.isFinite(cursorInput)) {
    return collapsedLength;
  }
  return Math.max(0, Math.min(collapsedLength, Math.floor(cursorInput)));
}

export function clampCollapsedComposerCursor(text: string, cursorInput: number): number {
  return clampCollapsedComposerCursorForSegments(
    splitPromptIntoComposerSegments(text),
    cursorInput,
  );
}

export function collapseExpandedComposerCursor(text: string, cursorInput: number): number {
  const expandedCursor = clampCursor(text, cursorInput);
  const segments = splitPromptIntoComposerSegments(text);
  if (segments.length === 0) {
    return expandedCursor;
  }

  let remaining = expandedCursor;
  let collapsedCursor = 0;

  for (const segment of segments) {
    if (segment.type === "mention") {
      const expandedLength = segment.path.length + 1;
      if (remaining === 0) {
        return collapsedCursor;
      }
      if (remaining <= expandedLength) {
        return collapsedCursor + 1;
      }
      remaining -= expandedLength;
      collapsedCursor += 1;
      continue;
    }
    if (segment.type === "skill") {
      const expandedLength = segment.name.length + 1;
      if (remaining === 0) {
        return collapsedCursor;
      }
      if (remaining <= expandedLength) {
        return collapsedCursor + 1;
      }
      remaining -= expandedLength;
      collapsedCursor += 1;
      continue;
    }
    if (segment.type === "terminal-context") {
      if (remaining <= 1) {
        return collapsedCursor + remaining;
      }
      remaining -= 1;
      collapsedCursor += 1;
      continue;
    }

    const segmentLength = segment.text.length;
    if (remaining <= segmentLength) {
      return collapsedCursor + remaining;
    }
    remaining -= segmentLength;
    collapsedCursor += segmentLength;
  }

  return collapsedCursor;
}

export function isCollapsedCursorAdjacentToInlineToken(
  text: string,
  cursorInput: number,
  direction: "left" | "right",
): boolean {
  const segments = splitPromptIntoComposerSegments(text);
  if (!segments.some(isInlineTokenSegment)) {
    return false;
  }

  const cursor = clampCollapsedComposerCursorForSegments(segments, cursorInput);
  let collapsedOffset = 0;

  for (const segment of segments) {
    if (isInlineTokenSegment(segment)) {
      if (direction === "left" && cursor === collapsedOffset + 1) {
        return true;
      }
      if (direction === "right" && cursor === collapsedOffset) {
        return true;
      }
    }
    collapsedOffset += collapsedSegmentLength(segment);
  }

  return false;
}

export const isCollapsedCursorAdjacentToMention = isCollapsedCursorAdjacentToInlineToken;

export function detectComposerTrigger(text: string, cursorInput: number): ComposerTrigger | null {
  return detectComposerTriggerBase(text, cursorInput, isWhitespace);
}