import { randomUUID } from "crypto";
import {
  BaseExecutor,
  setUserAgentHeader,
  type ExecuteInput,
  type ProviderCredentials,
} from "./base.ts";
import { PROVIDERS } from "../config/constants.ts";
import { getModelTargetFormat } from "../config/providerModels.ts";
import {
  injectReasoningContentForThinkingModel,
  isThinkingMessageModel,
} from "../utils/reasoningContentInjector.ts";
import { runWithProxyContext } from "../utils/proxyFetch.ts";

/**
 * Per-account proxy configuration, persisted by NoAuthAccountCard under
 * `providerSpecificData.accountProxies` (keyed by the account id, which the UI
 * stores in `providerSpecificData.fingerprints`). Same shape mimocode uses.
 */
export interface OpencodeAccountProxyConfig {
  fingerprint: string;
  proxy: {
    type: string;
    host: string;
    port: number;
    username?: string;
    password?: string;
  } | null;
}

/** Runtime rotation/cooldown state for one "OpenCode Free" account. */
interface OpencodeAccountState {
  /** Account id (UI: providerSpecificData.fingerprints[i]); "" for the default direct account. */
  fingerprint: string;
  cooldownUntil: number;
  consecutiveFails: number;
  /** Resolved proxy config for this account (null = direct egress). */
  proxy: OpencodeAccountProxyConfig["proxy"];
}

const OPENCODE_COOLDOWN_BASE_MS = 5_000;
const OPENCODE_COOLDOWN_MAX_MS = 60_000;

export class OpencodeExecutor extends BaseExecutor {
  _requestFormat: string | null = null;

  /**
   * Per-account rotation state, rebuilt from credentials on each request. The
   * default entry (fingerprint "") represents the single anonymous account with
   * no configured proxy — preserves the historical direct pass-through when the
   * user has not configured any per-account proxy.
   */
  private accounts: OpencodeAccountState[] = [
    { fingerprint: "", cooldownUntil: 0, consecutiveFails: 0, proxy: null },
  ];
  private nextAccountIdx = 0;

  constructor(provider: string) {
    super(provider, PROVIDERS[provider] || PROVIDERS.openai);
  }

  /**
   * Rebuild `accounts` from `providerSpecificData.fingerprints` +
   * `providerSpecificData.accountProxies`. Each configured account id becomes a
   * rotation slot carrying its own proxy. When the user configured no accounts
   * at all, the single default direct account is kept (backward compatible).
   */
  private syncAccountsFromCredentials(credentials: ProviderCredentials): void {
    const psd = credentials?.providerSpecificData;
    const fingerprints = Array.isArray(psd?.fingerprints)
      ? (psd!.fingerprints as unknown[]).filter((f): f is string => typeof f === "string")
      : [];

    const accountProxies = psd?.accountProxies as OpencodeAccountProxyConfig[] | undefined;
    const proxyMap = Array.isArray(accountProxies)
      ? new Map(accountProxies.map((ap) => [ap.fingerprint, ap.proxy ?? null] as const))
      : null;

    if (fingerprints.length === 0) {
      // No configured accounts — keep a single direct account.
      this.accounts = [{ fingerprint: "", cooldownUntil: 0, consecutiveFails: 0, proxy: null }];
      this.nextAccountIdx = 0;
      return;
    }

    const previous = new Map(this.accounts.map((a) => [a.fingerprint, a] as const));
    this.accounts = fingerprints.map((fp) => {
      const prior = previous.get(fp);
      return {
        fingerprint: fp,
        cooldownUntil: prior?.cooldownUntil ?? 0,
        consecutiveFails: prior?.consecutiveFails ?? 0,
        proxy: proxyMap ? (proxyMap.get(fp) ?? null) : null,
      };
    });
    if (this.nextAccountIdx >= this.accounts.length) this.nextAccountIdx = 0;
  }

  private isAccountReady(account: OpencodeAccountState): boolean {
    return account.cooldownUntil <= Date.now();
  }

  /** Round-robin pick, skipping accounts in cooldown; falls back to the next index. */
  private pickAccount(): OpencodeAccountState {
    for (let i = 0; i < this.accounts.length; i++) {
      const idx = (this.nextAccountIdx + i) % this.accounts.length;
      const acct = this.accounts[idx];
      if (this.isAccountReady(acct)) {
        this.nextAccountIdx = (idx + 1) % this.accounts.length;
        return acct;
      }
    }
    const fallbackIdx = this.nextAccountIdx % this.accounts.length;
    this.nextAccountIdx = (this.nextAccountIdx + 1) % this.accounts.length;
    return this.accounts[fallbackIdx];
  }

  private markCooldown(account: OpencodeAccountState): void {
    account.consecutiveFails++;
    const backoff = Math.min(
      OPENCODE_COOLDOWN_BASE_MS * Math.pow(2, account.consecutiveFails - 1),
      OPENCODE_COOLDOWN_MAX_MS
    );
    account.cooldownUntil = Date.now() + backoff + Math.random() * 1000;
  }

  private markSuccess(account: OpencodeAccountState): void {
    account.consecutiveFails = 0;
  }

  /** Mask an account id for logs (UI calls it a fingerprint). */
  private static maskAccountId(fingerprint: string): string {
    if (!fingerprint) return "direct";
    return `${fingerprint.slice(0, 8)}…`;
  }

  async execute(input: ExecuteInput) {
    this._requestFormat = getModelTargetFormat(this.provider, input.model) || "openai";
    try {
      this.syncAccountsFromCredentials(input.credentials);

      const hasProxies = this.accounts.some((a) => a.proxy !== null);
      // Fast path: no multi-account proxy wiring configured → original behavior.
      if (this.accounts.length === 1 && !hasProxies) {
        return await super.execute(input);
      }

      const { log } = input;
      let lastResult: Awaited<ReturnType<BaseExecutor["execute"]>> | null = null;

      for (let attempt = 0; attempt < this.accounts.length; attempt++) {
        const account = this.pickAccount();
        const masked = OpencodeExecutor.maskAccountId(account.fingerprint);
        // #5217 (Gap 2): promoted debug→info so the per-request account/proxy
        // rotation selection is visible in the Console log view at the default
        // APP_LOG_LEVEL=info (users could not see which account/proxy was used).
        // Token stays masked — never log the full account id.
        log?.info?.(
          "OPENCODE",
          `dispatch via account ${masked} (idx ${attempt + 1}/${this.accounts.length})` +
            (account.proxy ? ` through proxy ${account.proxy.host}:${account.proxy.port}` : " direct")
        );

        // Pin egress to this account's proxy for the whole BaseExecutor dispatch
        // (incl. its intra-URL 429 retries). skipUpstreamRetry lets THIS loop own
        // the cross-account 429 fallback instead of BaseExecutor's same-key retry.
        const result = await runWithProxyContext(account.proxy, () =>
          super.execute({ ...input, skipUpstreamRetry: true })
        );
        lastResult = result;

        const status = result.response.status;
        if (status === 429) {
          this.markCooldown(account);
          log?.warn?.(
            "OPENCODE",
            `Rate limited (429) on account ${masked}, rotating to next…`
          );
          continue;
        }

        this.markSuccess(account);
        return result;
      }

      // All accounts returned 429 (or errored) — surface the last response.
      return lastResult ?? (await super.execute(input));
    } finally {
      this._requestFormat = null;
    }
  }

  buildUrl(
    model: string,
    stream: boolean,
    urlIndex = 0,
    credentials: ProviderCredentials | null = null
  ) {
    void urlIndex;
    void credentials;

    const base = this.config.baseUrl;
    switch (this._requestFormat) {
      case "claude":
        return `${base}/messages`;
      case "openai-responses":
        return `${base}/responses`;
      case "gemini":
        return `${base}/models/${model}:${stream ? "streamGenerateContent?alt=sse" : "generateContent"}`;
      default:
        return `${base}/chat/completions`;
    }
  }

  buildHeaders(
    credentials: ProviderCredentials | null,
    stream = true,
    clientHeaders?: Record<string, string> | null,
    model?: string
  ) {
    const headers: Record<string, string> = { "Content-Type": "application/json" };
    const key = credentials?.apiKey || credentials?.accessToken;

    if (key) {
      if (this._requestFormat === "claude") {
        headers["x-api-key"] = key;
      } else {
        headers["Authorization"] = `Bearer ${key}`;
      }
    }

    if (this._requestFormat === "claude") {
      headers["anthropic-version"] = "2023-06-01";
    }

    if (stream) {
      headers["Accept"] = "text/event-stream";
    }

    if (clientHeaders) {
      const clientUA = clientHeaders["User-Agent"] || clientHeaders["user-agent"];
      if (clientUA) {
        setUserAgentHeader(headers, clientUA);
      }

      // Forward OpenCode request metadata headers from client
      const findClientHeader = (name: string) =>
        Object.entries(clientHeaders).find(
          ([key]) => key.toLowerCase() === name.toLowerCase()
        )?.[1];

      const opencodeHeaderKeys = [
        "x-opencode-session",
        "x-opencode-request",
        "x-opencode-project",
        "x-opencode-client",
      ];
      for (const headerName of opencodeHeaderKeys) {
        const value = findClientHeader(headerName);
        if (value) {
          headers[headerName] = value;
        }
      }

      // #4022: OpenCode CLI only emits x-opencode-* headers when the provider id
      // starts with "opencode". For a custom-named provider (e.g. "omniroute") it
      // instead sends x-session-affinity / X-Session-Id, which both carry the same
      // OpenCode sessionID. Map that session id onto x-opencode-session so session
      // continuity to the opencode.ai upstream works regardless of how the user
      // named the provider. Scoped to this executor (opencode.ai/zen upstreams
      // only) — the generic DefaultExecutor intentionally does NOT do this, to
      // avoid leaking the client session id to arbitrary third-party upstreams.
      if (!headers["x-opencode-session"]) {
        const sessionAffinity =
          findClientHeader("x-session-affinity") || findClientHeader("x-session-id");
        if (sessionAffinity) {
          headers["x-opencode-session"] = sessionAffinity;

          // #4465: a custom-named provider only reaches this fallback because the
          // OpenCode CLI did NOT emit the x-opencode-* set (it only does so when the
          // provider id starts with "opencode"). It therefore also dropped
          // x-opencode-request, a per-request correlation id. Synthesize one so these
          // users are not disadvantaged versus opencode-prefixed providers on the
          // opencode.ai upstream. x-opencode-client / x-opencode-project are NOT
          // fabricated: their valid values are opencode-internal and inventing them
          // could be rejected upstream — they remain forward-only above. Scoped to this
          // executor (opencode.ai/zen) and only to the fallback path, so the direct
          // OpenCode CLI flow (which controls its own request id) is untouched.
          if (!headers["x-opencode-request"]) {
            headers["x-opencode-request"] = randomUUID();
          }
        }
      }
    }

    void model;

    return headers;
  }

  transformRequest(
    model: string,
    body: any,
    stream: boolean,
    credentials: ProviderCredentials
  ): any {
    let modifiedBody = super.transformRequest(model, body, stream, credentials);
    if (
      modifiedBody &&
      typeof modifiedBody === "object" &&
      Array.isArray(modifiedBody.tools) &&
      modifiedBody.tools.length > 128
    ) {
      modifiedBody.tools = modifiedBody.tools.slice(0, 128);
    }
    if (modifiedBody && typeof modifiedBody === "object" && !Array.isArray(modifiedBody)) {
      const mb = modifiedBody as Record<string, unknown>;
      const m = String(model || "");
      const effortLevels = ["low", "medium", "high", "max"] as const;
      const matchedLevel = effortLevels.find((level) => m.endsWith(`-${level}`));
      if (matchedLevel) {
        const base = m.slice(0, -matchedLevel.length - 1);
        if (base.toLowerCase() === "deepseek-v4-pro") {
          mb.model = "deepseek-v4-pro";
          if (mb.reasoning_effort === undefined) {
            mb.reasoning_effort = matchedLevel;
          }
        }
      }
    }
    // #1543 / upstream PR #1099: thinking-mode upstreams routed through OpenCode
    // (DeepSeek V4 Flash, Kimi, MiniMax, ...) require reasoning_content echoed
    // back on assistant messages, or they 400 with "reasoning_content must be
    // passed back". OpenAI clients drop it across turns, so we inject a
    // placeholder for the affected model families.
    if (isThinkingMessageModel(model)) {
      modifiedBody = injectReasoningContentForThinkingModel(modifiedBody);
    }
    return modifiedBody;
  }
}