import { splitLines } from "../git/merge3";
import { hunkQuestionId } from "./decide";
import type { ClefRequest, ClefResponse } from "./decide";
import type { MergeFixProvider } from "./plan";

const SECURITY_HINT = /password|secret|token|auth|crypto|permission/i;

/** Union of both sides' lines, keeping head order first: a plausible deterministic "AI" resolution. */
function unionLines(ours: string, theirs: string): string {
  const lines = splitLines(ours);
  const seen = new Set(lines);
  for (const line of splitLines(theirs)) if (!seen.has(line)) lines.push(line);
  return lines.join("");
}

function spread(ids: string[], pick: string, top: number): Record<string, number> {
  const rest = ids.length > 1 ? (1 - top) / (ids.length - 1) : 0;
  return Object.fromEntries(ids.map((id) => [id, id === pick ? top : rest]));
}

/**
 * Deterministic stand-in for the generative model and Clef, selected with MERGEFIX_PROVIDER=mock. It picks
 * the first AI candidate with high confidence and flags anything that mentions credentials as security-sensitive.
 */
export function mockProvider(): MergeFixProvider {
  return {
    async generate({ hunk }) {
      return {
        text: `\`\`\`merge\n${unionLines(hunk.ours, hunk.theirs)}\`\`\``,
        usage: { inputTokens: 100, outputTokens: 20 },
      };
    },
    async decide(request: ClefRequest): Promise<ClefResponse> {
      const answers: ClefResponse["answers"] = {};
      for (const [id, question] of Object.entries(request.questions)) {
        if (question.type !== "choice") continue;
        const ids = Object.keys(question.criteria);
        const pick =
          ids.find((option) => option.startsWith("ai_")) ??
          ids.find((option) => option === "ours_then_theirs") ??
          ids[0];
        const probabilities = spread(ids, pick, 0.9);
        answers[id] = { type: "choice", choice: pick, probabilities, confidence: 0.9 };
      }
      const sensitive = SECURITY_HINT.test(JSON.stringify(request.state));
      const risk = sensitive ? [0.05, 0.15, 0.8] : [0.9, 0.08, 0.02];
      answers.risk = {
        type: "score",
        score: risk[1] + 2 * risk[2],
        probabilities: { "0": risk[0], "1": risk[1], "2": risk[2] },
        confidence: Math.max(...risk),
      };
      answers.needs_human = { type: "noul", noul: sensitive ? 0.7 : 0.05 };
      if (!answers[hunkQuestionId(0)]) answers.needs_human = { type: "noul", noul: 1 };
      return { answers, usage: { input_tokens: 500, output_tokens: 0 } };
    },
  };
}