import fs from "node:fs";
import os from "node:os";
import path from "node:path";

import { repoRoot } from "./core.mjs";

const orchExecutableName = process.platform === "win32" ? "orch.exe" : "orch";

export const defaultDbPath = path.join(repoRoot, ".artifacts", "orch", "coord.db");
export const defaultWorkspaceRoot = path.join(repoRoot, ".artifacts", "orch", "worktrees");
export const defaultTaskBodyRoot = path.join(repoRoot, ".artifacts", "orch", "task-bodies");
export const legacyOrchBinPath = path.join(
  os.homedir(),
  ".codex",
  "skills",
  "orch",
  "assets",
  orchExecutableName
);

function searchPathForExecutable(pathValue, existsSync = fs.existsSync) {
  if (!pathValue) {
    return null;
  }

  for (const entry of pathValue.split(path.delimiter)) {
    if (!entry) {
      continue;
    }

    const candidate = path.join(entry, orchExecutableName);

    if (existsSync(candidate)) {
      return candidate;
    }
  }

  return null;
}

export function resolveOrchBinary({ env = process.env, existsSync = fs.existsSync } = {}) {
  const checkedPaths = [];
  const explicitPath = env.CADENCE_UI_ORCH_BIN ? path.resolve(env.CADENCE_UI_ORCH_BIN) : null;

  if (explicitPath) {
    checkedPaths.push(explicitPath);

    if (existsSync(explicitPath)) {
      return {
        binaryPath: explicitPath,
        checkedPaths,
        source: "CADENCE_UI_ORCH_BIN"
      };
    }
  }

  const pathMatch = searchPathForExecutable(env.PATH ?? "", existsSync);

  if (pathMatch) {
    checkedPaths.push(pathMatch);
    return {
      binaryPath: pathMatch,
      checkedPaths,
      source: "PATH"
    };
  }

  checkedPaths.push(legacyOrchBinPath);

  if (existsSync(legacyOrchBinPath)) {
    return {
      binaryPath: legacyOrchBinPath,
      checkedPaths,
      source: "legacy"
    };
  }

  return {
    binaryPath: null,
    checkedPaths,
    source: null
  };
}

function parseTaskToken(token) {
  const [taskIdPart, dependencyPart] = token.split("->").map((value) => value.trim());

  return {
    dependsOn: dependencyPart
      ? dependencyPart
          .split(",")
          .map((value) => value.trim())
          .filter(Boolean)
      : [],
    id: taskIdPart
  };
}

export function parsePlanTaskSketch(markdown) {
  const lines = markdown.split(/\r?\n/);
  const planTitle =
    lines
      .find((line) => line.startsWith("# "))
      ?.slice(2)
      .trim() ?? "Execution Plan";
  const tasks = [];
  let inTaskSketch = false;

  for (const line of lines) {
    if (line.startsWith("## ")) {
      if (inTaskSketch) {
        break;
      }

      inTaskSketch = line.trim() === "## Orchestration Task Sketch";
      continue;
    }

    if (!inTaskSketch) {
      continue;
    }

    const match = line.match(/^\s*-\s+(?:`([^`]+)`|([^:]+)):\s+(.+)$/);

    if (!match) {
      continue;
    }

    const taskToken = (match[1] ?? match[2]).trim();
    const taskTitle = match[3].trim();
    const task = parseTaskToken(taskToken);

    tasks.push({
      ...task,
      title: taskTitle
    });
  }

  return {
    planTitle,
    tasks
  };
}

export function readPlanFile(planFile) {
  const absolutePath = path.isAbsolute(planFile) ? planFile : path.join(repoRoot, planFile);
  const markdown = fs.readFileSync(absolutePath, "utf8");
  const parsed = parsePlanTaskSketch(markdown);

  return {
    ...parsed,
    absolutePath,
    relativePath: path.relative(repoRoot, absolutePath)
  };
}

export function renderTaskBody({ plan, task }) {
  return `# ${task.id} — ${task.title}

- Source plan: \`${plan.relativePath}\`
- Plan title: ${plan.planTitle}
- Task id: ${task.id}
- Dependencies: ${task.dependsOn.length > 0 ? task.dependsOn.join(", ") : "none"}

## Execution Notes

- Read the source execution plan before editing.
- Keep this task scoped to the work implied by the task title and dependencies.
- Run the narrowest useful harness suites first, then report what broader validation remains.
- Return any shared integration follow-up instead of editing unrelated surfaces opportunistically.
`;
}

function sanitizeSegment(value) {
  return value.replace(/[^a-zA-Z0-9._-]+/g, "-");
}

export function writeTaskBodyFile({ bodyRoot = defaultTaskBodyRoot, plan, runId, task }) {
  const runDir = path.join(bodyRoot, sanitizeSegment(runId));
  const outputPath = path.join(runDir, `${sanitizeSegment(task.id)}.md`);

  fs.mkdirSync(runDir, { recursive: true });
  fs.writeFileSync(outputPath, `${renderTaskBody({ plan, task })}\n`, "utf8");

  return outputPath;
}