import { execSync, spawn } from "node:child_process";
import * as fs from "node:fs";
import * as path from "node:path";
import * as os from "node:os";
import {
  IntelligenceBackend,
  BackendRequest,
  BackendResult,
  BackendType,
  OpencodeBackendConfig,
  emptyTokenUsage,
  emptyBackendResult,
} from "./types.js";

export class OpencodeBackend implements IntelligenceBackend {
  readonly name = "opencode";
  readonly type: BackendType = "agent";

  private config: OpencodeBackendConfig;

  constructor(config?: OpencodeBackendConfig) {
    this.config = config || { enabled: true };
  }

  async isAvailable(): Promise<boolean> {
    const executable = this.config.executable || "opencode";
    try {
      const result = execSync(`${executable} --version`, {
        encoding: "utf-8",
        timeout: 5000,
        stdio: "pipe",
      });
      return !!result;
    } catch {
      return false;
    }
  }

  async execute(request: BackendRequest): Promise<BackendResult> {
    const executable = this.config.executable || "opencode";
    const startTime = Date.now();

    try {
      const serializedRequest = this.serializeRequest(request);
      const tempFile = path.join(
        os.tmpdir(),
        `ci-request-${request.persona}-${Date.now()}.json`
      );

      fs.writeFileSync(tempFile, serializedRequest, "utf-8");

      const command = `${executable} --non-interactive "/ci-${request.workflow} ${request.task}"`;
      const contextEnv = {
        ...process.env,
        CI_BACKEND_REQUEST: tempFile,
        CI_PROJECT_PATH: request.context.project_path,
        CI_PHASE: String(request.context.phase),
        CI_STAGE: request.context.stage,
        CI_AUTONOMY: request.autonomy,
      };

      const result = execSync(command, {
        cwd: request.context.project_path,
        encoding: "utf-8",
        timeout: 600000,
        env: contextEnv,
        stdio: ["pipe", "pipe", "pipe"],
        maxBuffer: 10 * 1024 * 1024,
      });

      try {
        fs.unlinkSync(tempFile);
      } catch {}

      return this.parseResult(result, Date.now() - startTime);
    } catch (err) {
      const execErr = err as { stderr?: string; status?: number };

      try {
        const tempFile = path.join(
          os.tmpdir(),
          `ci-request-${request.persona}-${startTime}.json`
        );
        if (fs.existsSync(tempFile)) fs.unlinkSync(tempFile);
      } catch {}

      if (execErr.stderr) {
        return emptyBackendResult(
          `opencode execution failed (exit ${execErr.status || "unknown"}): ${execErr.stderr}`
        );
      }

      return emptyBackendResult(
        `opencode backend error: ${err instanceof Error ? err.message : String(err)}`
      );
    }
  }

  private serializeRequest(request: BackendRequest): string {
    return JSON.stringify({
      persona: request.persona,
      workflow: request.workflow,
      task: request.task,
      context: {
        project_path: request.context.project_path,
        phase: request.context.phase,
        stage: request.context.stage,
        specification: request.context.specification,
        config_path: request.context.config_path,
      },
      autonomy: request.autonomy,
    }, null, 2);
  }

  private parseResult(output: string, durationMs: number): BackendResult {
    const jsonMatch = output.match(/\{[\s\S]*"success"[\s\S]*\}/);
    if (jsonMatch) {
      try {
        const parsed = JSON.parse(jsonMatch[0]);
        return {
          success: parsed.success ?? true,
          output: parsed.output || output,
          artifacts: Array.isArray(parsed.artifacts)
            ? parsed.artifacts.filter((a: unknown) => !!a).map((a: Record<string, unknown>) => ({
                path: String(a.path || ""),
                content: String(a.content || ""),
                operation: (a.operation as "create" | "update" | "delete") || "create",
              }))
            : [],
          decisions: Array.isArray(parsed.decisions)
            ? parsed.decisions.filter((d: unknown) => !!d).map((d: Record<string, unknown>) => ({
                id: String(d.id || "D-000"),
                decision: String(d.decision || ""),
                rationale: String(d.rationale || ""),
                confidence: Number(d.confidence || 0.5),
                category: (d.category as "implementation_approach" | "technology_choice" | "architecture" | "scope" | "verification" | "security" | "deployment" | "general") || "general",
                alternatives_considered: Array.isArray(d.alternatives_considered)
                  ? d.alternatives_considered.map((a: unknown) =>
                      typeof a === "string"
                        ? { option: a, rejected_reason: "" }
                        : (a as { option: string; rejected_reason: string })
                    )
                  : [],
                learnship_equivalent: String(d.learnship_equivalent || ""),
                human_override: d.human_override ? String(d.human_override) : null,
                timestamp: String(d.timestamp || new Date().toISOString()),
              }))
            : [],
          escalations: Array.isArray(parsed.escalations)
            ? parsed.escalations.filter((e: unknown) => !!e).map((e: Record<string, unknown>) => ({
                id: String(e.id || "E-000"),
                timestamp: String(e.timestamp || new Date().toISOString()),
                type: (e.type as "irreversible_action" | "verification_failure" | "low_confidence_decision" | "security_escalation" | "specification_ambiguity") || "specification_ambiguity",
                phase: String(e.phase || ""),
                description: String(e.description || ""),
                context: String(e.context || ""),
                options: Array.isArray(e.options) ? e.options : [],
                default_option_id: String(e.default_option_id || ""),
                resolution: (e.resolution as "approved" | "rejected" | "modified" | "pending" | "timeout_auto_proceed") || "pending",
                audit_file: String(e.audit_file || ""),
              }))
            : [],
          usage: parsed.usage || {
            ...emptyTokenUsage(),
            total_tokens: Math.ceil(output.length / 4),
          },
        };
      } catch {}
    }

    return {
      success: true,
      output,
      artifacts: [],
      decisions: [],
      escalations: [],
      usage: {
        ...emptyTokenUsage(),
        total_tokens: Math.ceil(output.length / 4),
      },
    };
  }
}