import { existsSync } from "node:fs";
import { join } from "node:path";
import type { ActiveRun } from "./types.ts";
import { runRoot } from "./paths.ts";
import { hasEvidenceEntry } from "./evidence.ts";

export interface PlanStep {
	id: string;
	text: string;
}

const STEP_LINE_PATTERN = /^\s*[-*]\s*\[[ xX]\]\s*(STEP-\d{3,})\s*[:：]\s*(.+)$/gim;
const EVIDENCE_PATTERN = /\bevidence[\\/][^\s`"')]+/gi;

export function parsePlanSteps(plan: string): PlanStep[] {
	const steps: PlanStep[] = [];
	for (const match of plan.matchAll(STEP_LINE_PATTERN)) {
		steps.push({ id: match[1].toUpperCase(), text: match[2].trim() });
	}
	return steps;
}

export function planStepsBlockReason(plan: string): string | undefined {
	if (!/##\s*执行步骤/i.test(plan)) {
		return "PLAN.md 缺少 ## 执行步骤。下一步：回到 plan，补充 `## 执行步骤`；使用 `- [ ] STEP-001：...` 拆分可跟踪步骤；每一步必须产生代码变更或 evidence。";
	}

	const steps = parsePlanSteps(plan);
	if (steps.length === 0) {
		return "PLAN.md 没有可执行步骤。下一步：在 `## 执行步骤` 下使用 `- [ ] STEP-001：...` 列出步骤；禁止用普通段落代替可勾选步骤。";
	}

	const duplicate = firstDuplicate(steps.map((step) => step.id));
	if (duplicate) return `PLAN.md 存在重复步骤编号：${duplicate}。下一步：重新编号执行步骤，确保 STEP-001、STEP-002 等编号唯一且顺序稳定。`;
	return undefined;
}

export function executionStepsBlockReason(cwd: string, run: ActiveRun, plan: string, execution: string): string | undefined {
	const steps = parsePlanSteps(plan);
	if (steps.length === 0) return planStepsBlockReason(plan);

	const missing: string[] = [];
	const missingEvidence: string[] = [];

	for (const step of steps) {
		const line = findExecutionLine(execution, step.id);
		if (!line) {
			missing.push(step.id);
			continue;
		}

		const evidencePaths = [...line.matchAll(EVIDENCE_PATTERN)].map((match) => normalizeEvidencePath(match[0]));
		if (evidencePaths.length === 0 || !evidencePaths.some((path) => existsSync(join(runRoot(cwd, run), path)) && hasEvidenceEntry(cwd, run, path))) {
			missingEvidence.push(step.id);
		}
	}

	if (missing.length > 0) {
		return `不能进入 verify：EXECUTION.md 未完成计划步骤 ${missing.join(", ")}。下一步：执行缺失步骤；完成后在 EXECUTION.md 的 ## 步骤结果 中使用 \`- [x] STEP-###：已完成。证据：evidence/step-###.md\` 记录；未执行完成时禁止勾选。`;
	}
	if (missingEvidence.length > 0) {
		return `不能进入 verify：步骤 ${missingEvidence.join(", ")} 缺少已落地的 evidence 文件。下一步：为每个步骤创建真实 evidence 文件，写入检查命令、结果、改动文件或验证输出，然后在 EXECUTION.md 对应步骤行引用该 evidence 路径。`;
	}
	return undefined;
}

function findExecutionLine(execution: string, stepId: string): string | undefined {
	return execution
		.split(/\r?\n/)
		.find((line) => line.toUpperCase().includes(stepId) && /(\[[xX]\]|done|完成|completed)/i.test(line));
}

function firstDuplicate(values: string[]): string | undefined {
	const seen = new Set<string>();
	for (const value of values) {
		if (seen.has(value)) return value;
		seen.add(value);
	}
	return undefined;
}

function normalizeEvidencePath(path: string): string {
	return path.replace(/\\/g, "/").replace(/^\/+/, "");
}