// Pure transcript logic for the structured pane (#246) — the decisions
// docs/STRUCTURED-VIEW.md leaves to a client, kept out of the components so
// they can be tested without a DOM or a socket. Ported from structured.ts's
// private helpers and the parts of structuredRender.ts that were data, not
// markup.

import type {
  AcpContentBlock,
  AcpPermissionOption,
  AcpToolCallContent,
  ReducedState,
  StructuredApprovalDecision,
  TranscriptRow,
  TranscriptRowKind,
  TurnMeta,
} from "../../types.js";
import { computeDiffLines, diffStats } from "../../structuredDiff.js";

/** Human label behind a `ToolKind`. An unrecognised/absent kind is "Tool" —
 *  never a blank label. */
const KIND_LABEL: Record<string, string> = {
  read: "Read",
  edit: "Edit",
  delete: "Delete",
  move: "Move",
  search: "Search",
  execute: "Execute",
  think: "Think",
  fetch: "Fetch",
  switch_mode: "Switch mode",
};

export function toolKindLabel(kind: string | undefined): string {
  return (kind && KIND_LABEL[kind]) || "Tool";
}

/** Split a title into `{label, arg}` when it follows the adapter's own
 *  `Name(argument)` convention; otherwise the whole title is the arg and the
 *  tool's `kind` supplies a generic label. Never guesses at a shape the data
 *  doesn't actually show. */
export function splitToolTitle(
  title: string | undefined,
  name: string | null | undefined,
  kind: string | undefined,
): { label: string; arg: string } {
  const label = name ?? toolKindLabel(kind);
  if (!title) return { label, arg: "" };
  const m = /^(\S+)\(([\s\S]*)\)$/.exec(title);
  if (m) return { label: name ?? m[1], arg: m[2] };
  return { label, arg: title };
}

/** Content-block text, or a labelled placeholder for anything that isn't
 *  text — never dropped silently, never fabricated. */
export function contentBlockText(block: AcpContentBlock | undefined): string {
  if (!block) return "";
  switch (block.type) {
    case "text":
      return block.text;
    case "image":
      return "[image]";
    case "audio":
      return "[audio]";
    case "resource_link":
      return `[resource: ${block.name ?? block.uri ?? "linked"}]`;
    case "resource":
      return "[resource]";
    default:
      return "";
  }
}

/** `+added −removed` across every diff block in a tool call's content — real
 *  derived data, never a fabricated duration. */
export function toolDiffMeta(content: AcpToolCallContent[]): string {
  let added = 0;
  let removed = 0;
  for (const block of content) {
    if (block.type !== "diff") continue;
    const stats = diffStats(computeDiffLines(block.oldText, block.newText));
    added += stats.added;
    removed += stats.removed;
  }
  return `+${added} −${removed}`;
}

export function statusMeta(
  status: string | undefined,
  hasDiff: boolean,
): { text: string; kind: string } | null {
  if (status === "in_progress") return { text: "running", kind: "running" };
  if (status === "failed") return { text: "failed", kind: "failed" };
  if (status === "pending" && !hasDiff) return { text: "pending", kind: "pending" };
  return null;
}

/** The `maestroTurnMeta` footer a `Notice` row carries when it is a completed,
 *  cancelled or failed turn's durable footer — `null` for every other notice. */
export function turnMeta(row: TranscriptRow): TurnMeta | null {
  if (row.kind !== "notice" || !row.data || typeof row.data !== "object") return null;
  const value = (row.data as { maestroTurnMeta?: unknown }).maestroTurnMeta;
  if (!value || typeof value !== "object") return null;
  const meta = value as Partial<TurnMeta>;
  if (typeof meta.elapsedMs !== "number" || typeof meta.outcome !== "string") return null;
  return meta as TurnMeta;
}

/** Notices the web client consumes as state and omits from the visible
 *  transcript (docs/STRUCTURED-VIEW.md, "A client decides"). */
export function isStateOnlyNotice(row: TranscriptRow): boolean {
  if (row.kind !== "notice" || !row.data || typeof row.data !== "object") return false;
  const update = (row.data as { sessionUpdate?: string }).sessionUpdate;
  return update === "available_commands_update" || update === "session_info_update";
}

/** Which decisions a permission request actually backs, by the
 *  `PermissionOptionKind` values it offers (docs/STRUCTURED-VIEW.md's
 *  "Decision mapping"). A decision with no matching option resolves
 *  `Cancelled` server-side regardless of what the client sent — offering its
 *  button would let the operator "allow" something that silently no-ops. */
export function offeredDecisions(options: AcpPermissionOption[]): StructuredApprovalDecision[] {
  const kinds = new Set(options.map((o) => o.kind));
  const decisions: StructuredApprovalDecision[] = [];
  if (kinds.has("allow_once")) decisions.push("allow_once");
  if (kinds.has("allow_always")) decisions.push("allow_for_session");
  if (kinds.has("reject_once") || kinds.has("reject_always")) decisions.push("deny");
  return decisions;
}

/** The row id a live `pending_approval` names: the newest `Approval` row.
 *  Only one approval is ever live (docs/STRUCTURED-VIEW.md, "One live
 *  approval at a time"), so the last one is the pending one. */
export function pendingApprovalRowId(rows: TranscriptRow[], state: ReducedState): string | null {
  return state.pending_approval ? lastRowIdOfKind(rows, "approval") : null;
}

export function lastRowIdOfKind(rows: TranscriptRow[], kind: TranscriptRowKind): string | null {
  for (let i = rows.length - 1; i >= 0; i--) if (rows[i].kind === kind) return rows[i].id;
  return null;
}

export function turnIsActive(state: ReducedState): boolean {
  return state.turn.responding || state.turn.thinking;
}

export interface ActivityGroup {
  /** Header label count — tool rows only, never absorbed text. */
  toolCount: number;
  /** Tools plus absorbed intermediate text/approvals, in transcript order. */
  rows: TranscriptRow[];
}

/**
 * Group tool rows (and intermediate agent text / resolved approvals between
 * them) by turn. An agent_text/agent_thought row is "intermediate" when a tool
 * row follows it in the same turn — it gets absorbed into the group so the
 * collapsed block preserves chronological order. Resolved approval rows (not
 * the currently pending one) are absorbed the same way. The *last* agent text
 * with no subsequent tool stays standalone (the prominent final answer).
 *
 * Returns groups keyed by `turn:<userId>`.
 */
export function activityGroupsByTurn(
  rows: TranscriptRow[],
  pendingApprovalId: string | null,
  turnActive: boolean,
): Map<string, ActivityGroup> {
  // First: count tools per turn to know which turns qualify for grouping.
  const toolCounts = new Map<string, number>();
  let turnId = "before-first-message";
  for (const row of rows) {
    if (row.kind === "user") turnId = row.id;
    if (row.kind !== "tool_call" && row.kind !== "tool_diff") continue;
    const gid = `turn:${turnId}`;
    toolCounts.set(gid, (toolCounts.get(gid) ?? 0) + 1);
  }
  // Second: build groups with interleaved text for turns with 2+ tools.
  const groups = new Map<string, ActivityGroup>();
  turnId = "before-first-message";
  // Pending rows that might be intermediate (not yet confirmed by a following
  // tool). If no tool follows, they stay standalone.
  let pending: TranscriptRow[] = [];
  let currentGid = `turn:${turnId}`;
  for (const row of rows) {
    if (row.kind === "user") {
      turnId = row.id;
      currentGid = `turn:${turnId}`;
      pending = [];
      continue;
    }
    const count = toolCounts.get(currentGid) ?? 0;
    if (count < 2) continue;
    const isIntermediateText = row.kind === "agent_text" || row.kind === "agent_thought";
    const isResolvedApproval = row.kind === "approval" && row.id !== pendingApprovalId;
    if (isIntermediateText || isResolvedApproval) {
      pending.push(row);
      continue;
    }
    if (row.kind === "tool_call" || row.kind === "tool_diff") {
      const group = groups.get(currentGid) ?? { toolCount: count, rows: [] };
      // Flush any pending rows — a tool follows, so they're intermediate.
      group.rows.push(...pending);
      pending = [];
      group.rows.push(row);
      groups.set(currentGid, group);
    }
  }
  // A final agent text is the answer, so it stays outside. Thought rows are
  // working commentary, though: when a turn already has a disclosure they
  // belong with its activity even if the next tool call has not arrived yet.
  // While the turn is still live the most recent one stays outside as visible
  // narration (docs/STRUCTURED-VIEW.md), and is absorbed when the turn ends.
  const lastGroup = groups.get(currentGid);
  if (lastGroup && pending.length > 0 && pending.every((row) => row.kind === "agent_thought")) {
    const absorb = turnActive ? pending.slice(0, -1) : pending;
    lastGroup.rows.push(...absorb);
  }

  return groups;
}

/** One entry of the flattened render list: either a standalone row or a whole
 *  activity group. */
export type TranscriptItem =
  | { type: "row"; row: TranscriptRow }
  | { type: "group"; id: string; group: ActivityGroup };

/**
 * The transcript in render order: rows, with each turn's tool activity folded
 * into a single group item where one exists. Resolved approvals not absorbed
 * into a group are dropped — the tool row itself already identifies the
 * action. `plan` rows and state-only notices are dropped too (both clients
 * omit `Plan` from the transcript). A turn footer only survives as the final
 * item, so old footers stop reading like transcript content.
 */
export function transcriptItems(
  rows: TranscriptRow[],
  pendingApprovalId: string | null,
  turnActive: boolean,
): TranscriptItem[] {
  const groups = activityGroupsByTurn(rows, pendingApprovalId, turnActive);
  const grouped = new Set<string>();
  for (const group of groups.values()) for (const row of group.rows) grouped.add(row.id);

  const items: TranscriptItem[] = [];
  let turnId = "before-first-message";
  const emitted = new Set<string>();
  for (const row of rows) {
    if (row.kind === "user") turnId = row.id;
    const groupId = `turn:${turnId}`;
    const group = groups.get(groupId);
    if (group && grouped.has(row.id)) {
      // The group renders once, at its first member's position.
      if (!emitted.has(groupId)) {
        emitted.add(groupId);
        items.push({ type: "group", id: groupId, group });
      }
      continue;
    }
    if (row.kind === "plan") continue;
    if (row.kind === "notice" && isStateOnlyNotice(row)) continue;
    // A resolved approval outside a group adds nothing the tool row does not
    // already say. A pending one always renders.
    if (row.kind === "approval" && row.id !== pendingApprovalId) continue;
    items.push({ type: "row", row });
  }

  return items.filter(
    (item, index) =>
      !(item.type === "row" && turnMeta(item.row) !== null) || index === items.length - 1,
  );
}

// ---------------------------------------------------------------------------
// composer: `/` command autocomplete off `available_commands_update` notices
// ---------------------------------------------------------------------------

export interface AvailableCommand {
  name: string;
  description: string;
  input?: { hint?: string };
}

/** The live command list is whatever the most recent
 *  `available_commands_update` notice carries (docs/STRUCTURED-VIEW.md). */
export function commandsFromTranscript(rows: TranscriptRow[]): AvailableCommand[] {
  for (let i = rows.length - 1; i >= 0; i--) {
    if (rows[i].kind !== "notice") continue;
    const data = rows[i].data as { sessionUpdate?: string; availableCommands?: unknown[] } | undefined;
    if (data?.sessionUpdate !== "available_commands_update") continue;
    return (data.availableCommands ?? []).flatMap((value) => {
      if (!value || typeof value !== "object") return [];
      const command = value as Partial<AvailableCommand>;
      if (typeof command.name !== "string" || typeof command.description !== "string") return [];
      return [{ name: command.name, description: command.description, input: command.input }];
    });
  }
  return [];
}

export interface CommandToken {
  start: number;
  end: number;
  query: string;
}

/** The whitespace-delimited token under the caret, when it is a `/command`
 *  being typed. Completing one replaces only that token. */
export function commandTokenAt(
  value: string,
  selectionStart: number,
  selectionEnd: number,
): CommandToken | null {
  if (selectionStart !== selectionEnd) return null;
  let start = selectionStart;
  while (start > 0 && !/\s/.test(value[start - 1])) start--;
  let end = selectionStart;
  while (end < value.length && !/\s/.test(value[end])) end++;
  const match = /^\/([^\s/]*)$/.exec(value.slice(start, selectionStart));
  return match ? { start, end, query: match[1].toLocaleLowerCase() } : null;
}

/** Substring match, prefix matches first, then alphabetical. */
export function filterCommands(commands: AvailableCommand[], query: string): AvailableCommand[] {
  return commands
    .filter((command) => command.name.toLocaleLowerCase().includes(query))
    .sort((a, b) => {
      const aStarts = a.name.toLocaleLowerCase().startsWith(query);
      const bStarts = b.name.toLocaleLowerCase().startsWith(query);
      return aStarts === bStarts ? a.name.localeCompare(b.name) : aStarts ? -1 : 1;
    });
}

/** Replace the token under the caret with `/name`, returning the new draft and
 *  where the caret lands. A trailing space is added only when the completion
 *  ends the draft. */
export function applyCommand(
  value: string,
  token: CommandToken,
  name: string,
): { value: string; cursor: number } {
  const before = value.slice(0, token.start);
  const after = value.slice(token.end);
  let replacement = `/${name}`;
  let cursor = before.length + replacement.length;
  if (after.length === 0) {
    replacement += " ";
    cursor++;
  } else if (/^[ \t]/.test(after)) {
    cursor++;
  }
  return { value: before + replacement + after, cursor };
}

// ---------------------------------------------------------------------------
// session config menu
// ---------------------------------------------------------------------------

/** Category order the config menu sorts by; anything else lands after. */
const CONFIG_CATEGORY_ORDER = ["model", "thought_level", "mode", "model_config"];

export function orderConfigOptions<T extends { category?: string | null }>(options: T[]): T[] {
  return [...options].sort((a, b) => {
    const rank = (category?: string | null) => CONFIG_CATEGORY_ORDER.indexOf(category ?? "");
    const aRank = rank(a.category);
    const bRank = rank(b.category);
    return (aRank < 0 ? 99 : aRank) - (bRank < 0 ? 99 : bRank);
  });
}