import type { Role, RoleResult, StartStep, WorkflowMessage } from "@uncaged/nerve-core";
import { cursorAgent, spawnSafe } from "@uncaged/nerve-workflow-utils";
import { lastMetaForRole } from "../../lib/meta-helpers.js";
import { formatSpawnFailure } from "../../lib/spawn-utils.js";
import { slugify } from "../../lib/text-utils.js";
import type { IntakeMeta } from "../intake/index.js";
import type { IssueReaderMeta } from "../issue-reader/index.js";
import type { PlannerMeta } from "../planner/index.js";
import { buildImplementerPrompt } from "./prompt.js";

export type ImplementerMeta = {
  branchName: string | null;
  changedFiles: string[] | null;
  implementationOk: boolean;
  attempt: number;
  failureKind: "none" | "branch_failed" | "agent_failed" | "no_diff";
  failureReason: string | null;
  implementationLog: string | null;
};

export type BuildImplementerDeps = {
  nerveRoot: string;
};

export function buildImplementerRole({ nerveRoot }: BuildImplementerDeps): Role<ImplementerMeta> {
  return async (_start: StartStep, messages: WorkflowMessage[]): Promise<RoleResult<ImplementerMeta>> => {
    const plannerMeta = lastMetaForRole<PlannerMeta>(messages, "planner");
    const intakeMeta = lastMetaForRole<IntakeMeta>(messages, "intake");
    const issueMeta = lastMetaForRole<IssueReaderMeta>(messages, "issue-reader");
    const attempt = messages.filter((message) => message.role === "implementer").length + 1;

    if (
      plannerMeta === null ||
      !plannerMeta.planningOk ||
      plannerMeta.plan === null ||
      intakeMeta === null ||
      intakeMeta.issueNumber === null
    ) {
      return {
        content: "implementer cannot continue: missing planner or intake context",
        meta: {
          branchName: null,
          changedFiles: null,
          implementationOk: false,
          attempt,
          failureKind: "agent_failed",
          failureReason: "missing planner/intake context",
          implementationLog: null,
        },
      };
    }

    const slugSource = issueMeta?.issue?.title ?? plannerMeta.plan.split("\n")[0] ?? "fix";
    const branchName = `fix/issue-${intakeMeta.issueNumber}-${slugify(slugSource)}`;

    const existsResult = await spawnSafe("git", ["rev-parse", "--verify", `refs/heads/${branchName}`], {
      cwd: nerveRoot,
      env: null,
      timeoutMs: 10_000,
    });
    const checkoutResult = existsResult.ok
      ? await spawnSafe("git", ["checkout", branchName], { cwd: nerveRoot, env: null, timeoutMs: 20_000 })
      : await spawnSafe("git", ["checkout", "-b", branchName], { cwd: nerveRoot, env: null, timeoutMs: 20_000 });

    if (!checkoutResult.ok) {
      return {
        content: `branch setup failed: ${formatSpawnFailure(checkoutResult.error)}`,
        meta: {
          branchName,
          changedFiles: null,
          implementationOk: false,
          attempt,
          failureKind: "branch_failed",
          failureReason: formatSpawnFailure(checkoutResult.error),
          implementationLog: null,
        },
      };
    }

    const prompt = buildImplementerPrompt({
      issueNumber: intakeMeta.issueNumber,
      plan: plannerMeta.plan,
      targetFilesText: plannerMeta.targetFiles?.join("\n") ?? "(not specified)",
      testCommandsText: plannerMeta.testCommands?.join("\n") ?? "(not specified)",
    });

    const agentResult = await cursorAgent({
      prompt,
      mode: "default",
      model: "auto",
      cwd: nerveRoot,
      env: null,
      timeoutMs: null,
    });
    if (!agentResult.ok) {
      return {
        content: `implementer agent failed: ${formatSpawnFailure(agentResult.error)}`,
        meta: {
          branchName,
          changedFiles: null,
          implementationOk: false,
          attempt,
          failureKind: "agent_failed",
          failureReason: formatSpawnFailure(agentResult.error),
          implementationLog: null,
        },
      };
    }

    const diffResult = await spawnSafe("git", ["diff", "--name-only"], {
      cwd: nerveRoot,
      env: null,
      timeoutMs: 15_000,
    });
    if (!diffResult.ok) {
      return {
        content: `implementation finished but diff check failed: ${formatSpawnFailure(diffResult.error)}`,
        meta: {
          branchName,
          changedFiles: null,
          implementationOk: false,
          attempt,
          failureKind: "no_diff",
          failureReason: formatSpawnFailure(diffResult.error),
          implementationLog: agentResult.value,
        },
      };
    }

    const changedFiles = diffResult.value.stdout
      .split("\n")
      .map((file) => file.trim())
      .filter((file) => file.length > 0);
    if (changedFiles.length === 0) {
      return {
        content: "implementer made no local diff",
        meta: {
          branchName,
          changedFiles: [],
          implementationOk: false,
          attempt,
          failureKind: "no_diff",
          failureReason: "git diff --name-only is empty",
          implementationLog: agentResult.value,
        },
      };
    }

    return {
      content: `branch ready: ${branchName}\nchanged files:\n${changedFiles.join("\n")}`,
      meta: {
        branchName,
        changedFiles,
        implementationOk: true,
        attempt,
        failureKind: "none",
        failureReason: null,
        implementationLog: agentResult.value,
      },
    };
  };
}