import { useCallback, useState } from 'react';

export type ChatSurfaceState = { anchorId: string; visibleProjectIds: string[]; visibleExperienceIds: string[]; visibleEducationIds: string[]; visibleLinkIds: string[]; focusedProjectId: string | null; highlightedSkills: string[]; lastActionAt: string | null; };

export type ChatUiState = { surfaces: ChatSurfaceState[]; };

export type ApplyUiActionOptions = { anchorItemId?: string | null; ui?: { showProjects?: string[]; showExperiences?: string[]; showLinks?: string[]; showEducation?: string[]; }; timestamp?: string; };

export function useChatUiState(initialState: ChatUiState = { surfaces: [] }) { const [uiState, setUiState] = useState(initialState);

const applyUiActions = useCallback((options?: ApplyUiActionOptions) => { setUiState((prev) => reduceChatUiState(prev, options)); }, []);

return { uiState, applyUiActions }; }

export function reduceChatUiState(prev: ChatUiState, options?: ApplyUiActionOptions): ChatUiState { if (!options?.anchorItemId && !options?.ui) { return prev; }

const anchorId = options?.anchorItemId ?? null; if (!anchorId) { return prev; }

const prevSurfaces = prev.surfaces ?? []; const existingIndex = prevSurfaces.findIndex((surface) => surface.anchorId === anchorId);

if (!options?.ui) { if (existingIndex === -1) { return prev; } const trimmed = prevSurfaces.filter((surface) => surface.anchorId !== anchorId); if (trimmed.length === prevSurfaces.length) { return prev; } return { surfaces: trimmed }; }

const baseSurface = existingIndex !== -1 ? prevSurfaces[existingIndex] : createEmptySurface(anchorId);

let nextVisible = baseSurface.visibleProjectIds ?? []; let nextVisibleExperiences = baseSurface.visibleExperienceIds ?? []; let nextVisibleEducation = baseSurface.visibleEducationIds ?? []; let nextVisibleLinks = baseSurface.visibleLinkIds ?? []; const nextFocused: string | null = null; const nextSkills: string[] = []; let mutated = false;

if (options?.ui) { if (Array.isArray(options.ui.showProjects)) { const dedupedProjects = dedupeIdentifiers(options.ui.showProjects); if (!arraysEqual(dedupedProjects, nextVisible)) { nextVisible = dedupedProjects; mutated = true; } }

if (Array.isArray(options.ui.showExperiences)) {
  const dedupedExperiences = dedupeIdentifiers(options.ui.showExperiences);
  if (!arraysEqual(dedupedExperiences, nextVisibleExperiences)) {
    nextVisibleExperiences = dedupedExperiences;
    mutated = true;
  }
}

if (Array.isArray(options.ui.showEducation)) {
  const dedupedEducation = dedupeIdentifiers(options.ui.showEducation);
  if (!arraysEqual(dedupedEducation, nextVisibleEducation)) {
    nextVisibleEducation = dedupedEducation;
    mutated = true;
  }
}

if (Array.isArray(options.ui.showLinks)) {
  const dedupedLinks = dedupeIdentifiers(options.ui.showLinks);
  if (!arraysEqual(dedupedLinks, nextVisibleLinks)) {
    nextVisibleLinks = dedupedLinks;
    mutated = true;
  }
}

}

const hasPayload = (nextVisible?.length ?? 0) > 0 || (nextVisibleExperiences?.length ?? 0) > 0 || (nextVisibleEducation?.length ?? 0) > 0 || (nextVisibleLinks?.length ?? 0) > 0 || Boolean(nextFocused);

if (!hasPayload) { if (existingIndex === -1) { return prev; } const trimmed = prevSurfaces.filter((surface) => surface.anchorId !== anchorId); if (trimmed.length === prevSurfaces.length) { return prev; } return { surfaces: trimmed }; }

if (!mutated && existingIndex !== -1) { return prev; }

const updatedSurface: ChatSurfaceState = { anchorId, visibleProjectIds: nextVisible, visibleExperienceIds: nextVisibleExperiences, visibleEducationIds: nextVisibleEducation, visibleLinkIds: nextVisibleLinks, focusedProjectId: nextFocused ?? null, highlightedSkills: nextSkills, lastActionAt: options?.timestamp ?? new Date().toISOString(), };

if (existingIndex !== -1) { const nextSurfaces = [...prevSurfaces]; nextSurfaces[existingIndex] = updatedSurface; return { surfaces: nextSurfaces }; }

return { surfaces: [...prevSurfaces, updatedSurface] }; }

function createEmptySurface(anchorId: string): ChatSurfaceState { return { anchorId, visibleProjectIds: [], visibleExperienceIds: [], visibleEducationIds: [], visibleLinkIds: [], focusedProjectId: null, highlightedSkills: [], lastActionAt: null, }; }

function dedupeIdentifiers(values?: string[]): string[] { if (!Array.isArray(values)) { return []; } const seen = new Set(); const ordered: string[] = []; for (const value of values) { const normalized = normalizeId(value); if (!normalized || seen.has(normalized)) { continue; } seen.add(normalized); ordered.push(normalized); } return ordered; }

function normalizeId(value?: string) { return typeof value === 'string' ? value.trim() : ''; }

function arraysEqual(a: string[], b: string[]) { if (a === b) { return true; } if (a.length !== b.length) { return false; } for (let idx = 0; idx < a.length; idx += 1) { if (a[idx] !== b[idx]) { return false; } } return true; }