/**
 * Command dispatcher — shared logic for parsing & dispatching commands
 * from text input or :cmd[] directive spans.
 *
 * Used by both JournalInput (manual typing) and CommandLinkManager (click).
 */

import { sendMessage } from "../stores/journalStream";
import { createSignal } from "solid-js";
import { parseInput } from "./command-parser";
import { resolveRollPayload } from "./types/roll";
import { resolveSparkPayload } from "./types/spark";
import { evaluateExpression, exprValueToString } from "./variable-expression";
import { computeCascade, getCombined, resolveVariable, setBase } from "./var-reactivity";
import { ensureReactivity } from "./completions";

// Tagmap pattern: "#warrior:1;#druid:2". Also accepts bare "#tag" as shorthand.
const BARE_TAG_PATTERN = /^#[a-zA-Z_][a-zA-Z0-9_]*$/;

function normalizeTagMap(expr: string): string {
  const t = expr.trim();
  if (BARE_TAG_PATTERN.test(t)) return t + ":1";
  return t;
}

// ---------------------------------------------------------------------------
// Result
// ---------------------------------------------------------------------------

export type DispatchResult = { ok: true } | { ok: false; error: string };

/**
 * Shared signal for dispatch errors from any source (typed or cmd-link clicks).
 * Components that show errors (JournalInput) read from here; callers that
 * want errors surfaced (CommandLinkManager) write to it.
 */
export const [dispatchError, setDispatchError] = createSignal<string | null>(
  null,
);

// ---------------------------------------------------------------------------
// Main dispatch
// ---------------------------------------------------------------------------

export interface DispatchContext {
  /** The role of the current user */
  role: "gm" | "player" | "observer";
  /** The user's name */
  myName: string;
  /** The raw text to dispatch (with or without leading `/`) */
  command: string;
  /** Spark table lookup data (from completions) */
  sparkTables: {
    slug: string;
    csvPath?: string;
    docPath?: string;
    remix?: boolean;
  }[];
  /** Current runtime variable values */
  variables: Record<string, string>;
}

/**
 * Dispatch a command string. Works for both typed input and
 * :cmd[] directive clicks.
 */
export async function dispatchCommand(
  ctx: DispatchContext,
): Promise<DispatchResult> {
  const raw = ctx.command.trim();
  if (!raw) return { ok: false, error: "Empty command" };

  // Make sure the engine reflects the currently loaded declarations; this
  // re-initializes only when they changed since the last dispatch.
  ensureReactivity();

  // Observers can only send chat
  if (ctx.role === "observer") {
    const result = sendMessage("chat", { text: raw });
    return finish(unwrap(result));
  }

  const prefixed = raw.startsWith("/") ? raw : "/" + raw;
  const parsed = parseInput(prefixed);
  if (parsed.error) return finish({ ok: false, error: parsed.error });

  // Players: chat + set commands only
  if (ctx.role === "player") {
    if (parsed.type === "chat") {
      const result = sendMessage("chat", { text: raw });
      return finish(unwrap(result));
    }

    if (parsed.type === "set" || parsed.type === "rolltag") {
      return finish(
        dispatchSet(parsed.payload as Record<string, unknown>, ctx),
      );
    }

    return finish({ ok: false, error: "玩家只能发送聊天消息或使用 /set 命令" });
  }

  // GM: all commands
  if (parsed.type === "roll") {
    const arg = (parsed.payload as { arg: string }).arg;

    // Try spark table first: if arg matches a known spark table slug, roll it
    const match = ctx.sparkTables.find((s) => s.slug === arg);
    if (match) {
      try {
        const csvPath = match.csvPath ?? "";
        const docPath = match.docPath;
        const remix = match.remix ?? false;
        const p = await resolveSparkPayload({
          key: arg,
          csvPath,
          docPath,
          remix,
        });
        const result = sendMessage("spark", p);
        return finish(unwrap(result));
      } catch (e) {
        return finish({
          ok: false,
          error: e instanceof Error ? e.message : "种子表掷骰失败",
        });
      }
    }

    // Variable expression (e.g. "2d6 + $mod" or "$hp / 2")
    if (arg.includes("$")) {
      try {
        const ev = evaluateExpression(arg, {
          // Strict: referencing an undefined variable is an error, not 0.
          lookup: (name) => resolveVariable(name, ctx.variables),
        });
        if (ev.value.kind !== "number") {
          return finish({ ok: false, error: "Roll expression must evaluate to a number" });
        }
        const payload = {
          notation: arg,
          label: arg,
          result: {
            total: ev.value.value,
            detail: "",
            plainDetail: "",
            pools: [] as { rolls: number[]; subtotal: number }[],
          },
        };
        const result = sendMessage("roll", payload);
        return finish(unwrap(result));
      } catch (e) {
        return finish({
          ok: false,
          error: e instanceof Error ? e.message : "表达式求值失败",
        });
      }
    }

    // Otherwise, treat as a dice expression
    const p = resolveRollPayload({ notation: arg, label: arg });
    const result = sendMessage("roll", p);
    return finish(unwrap(result));
  }

  if (parsed.type === "set" || parsed.type === "rolltag") {
    return finish(dispatchSet(parsed.payload as Record<string, unknown>, ctx));
  }

  const result = sendMessage(parsed.type, parsed.payload);
  return finish(unwrap(result));
}

/** Update the shared error signal and return the result (pass-through). */
function finish(r: DispatchResult): DispatchResult {
  setDispatchError(r.ok ? null : r.error);
  return r;
}

// ---------------------------------------------------------------------------
// Set dispatch
// ---------------------------------------------------------------------------

function dispatchSet(
  payload: Record<string, unknown>,
  ctx: DispatchContext,
): DispatchResult {
  const p = payload as { key?: string; expr?: string; tags?: string[] };

  if (!p.key) {
    return { ok: false, error: "缺少变量名" };
  }

  const key = p.key;
  // Use getCombined with stream fallback for old value so tag transitions
  // are detected correctly even when the variable has active mods.
  const oldValue = getCombined(key, ctx.variables);
  let newValue: string;

  try {
    if (p.tags && p.tags.length > 0) {
      // Rolltag: pick random tag, format as tagmap entry
      const idx = Math.floor(Math.random() * p.tags.length);
      newValue = normalizeTagMap(p.tags[idx]);
    } else if (p.expr) {
      // Evaluate expression — handles both numeric and tagmap values
      const result = evaluateExpression(p.expr, {
        // Strict: referencing an undefined variable is an error, not 0.
        lookup: (name) => resolveVariable(name, ctx.variables),
      });
      newValue = exprValueToString(result.value);
    } else {
      return { ok: false, error: "缺少表达式" };
    }
  } catch (e) {
    return {
      ok: false,
      error: e instanceof Error ? e.message : "表达式求值失败",
    };
  }

  // Update base value so getCombined returns the correct new value
  // during cascade computation
  setBase(key, newValue);

  // Build working variable store for cascade (includes the new value)
  const workingVars = { ...ctx.variables, [key]: newValue };

  // Compute cascade (tag activation/deactivation + declaration re-eval)
  try {
    const cascade = computeCascade(key, oldValue, workingVars);
    for (const change of cascade) {
      sendMessage("var", {
        action: "set",
        key: change.key,
        value: change.value,
        base: change.base,
      });
    }
  } catch (e) {
    // Cascade errors are non-fatal — the direct set already succeeded
    console.warn("[dispatch] cascade error:", e);
  }

  // Send the direct set last so cascade messages arrive first.
  // Publish the combined value for display plus the raw base so hydrated
  // clients can rebuild the engine exactly (see rebuildReactivityFromStore).
  const combinedValue = getCombined(key, ctx.variables);
  const r1 = sendMessage("var", {
    action: "set",
    key,
    value: combinedValue,
    base: newValue,
  });
  const u1 = unwrap(r1);
  if (!u1.ok) return u1;

  return { ok: true };
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

/** Unwrap a sendMessage result into DispatchResult. */
function unwrap<R>(
  r: { success: true; msg: R } | { success: false; error: string },
): DispatchResult {
  return r.success ? { ok: true } : { ok: false, error: r.error };
}