import { existsSync, mkdirSync, readFileSync, readdirSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import type { ExtensionAPI, ExtensionContext } from "@mariozechner/pi-coding-agent";
import { Type } from "typebox";
import { appendEvent, rebuildMetadataLight } from "./metadata.js";
import { searchWikiLayered } from "./recall.js";
import {
  type VaultPaths,
  fmtDate,
  nextTrajectoryId,
  readJson,
  resolveVaultPaths,
  writeJson,
} from "./utils.js";
import { assertWritableVault, inspectWritableVault } from "./vault-format.js";

/**
 * Agent trajectory memory — the working-memory half of the wiki.
 *
 * Where wiki_capture_source captures what the agent *read* (URLs, files, text),
 * wiki_capture_trajectory captures what the agent *did*: the sequence of
 * tool calls that solved a real task. Capture is deliberately lightweight — a
 * single call writes an immutable packet plus a SELF-CONTAINED summary
 * (extracted.md); it does NOT emit a to-be-fleshed skeleton (issue #80). The
 * optional distillation step then turns trajectories into reusable pages:
 *
 *   raw/trajectories/TRJ-* (immutable packet + self-contained summary)
 *     → wiki/skills/* (reusable pattern distilled from many trajectories)
 *     → wiki/cases/*  (a specific past task, written during distillation)
 *     → meta/*        (auto-generated registry/backlinks)
 */

// ─── Types ─────────────────────────────────────────────

/** A single normalized step in a captured trajectory. */
export interface TrajectoryStep {
  role: "user" | "assistant" | "tool";
  /** Free text (user prompt, assistant prose, or tool output preview). */
  text?: string;
  /** Tool calls issued by an assistant step. */
  tool_calls?: Array<{ id: string; name: string; arguments: unknown }>;
  /** Identifies which tool_call a tool step responds to. */
  tool_call_id?: string;
  /** Tool name for a tool step. */
  tool_name?: string;
  /** Whether a tool step reported an error. */
  is_error?: boolean;
}

export interface TrajectoryPacket {
  id: string;
  captured: string;
  packet_version: string;
  /** The prompt that started the task. */
  prompt: string;
  /** Model that ran the task, if known. */
  model?: string;
  steps: TrajectoryStep[];
}

export interface CaptureTrajectoryInput {
  /** Short descriptive title for the task. */
  title?: string;
  /** The task/prompt that started the work. Inferred from the session if omitted. */
  task?: string;
  /** Explicit trajectory steps. When omitted, extracted from the live session. */
  steps?: TrajectoryStep[];
  /** Model identifier, inferred from the session when available. */
  model?: string;
  /** Outcome label for the case skeleton. */
  outcome?: "success" | "failure" | "partial";
}

export interface CaptureTrajectoryResult {
  trajectoryId: string;
  packetPath: string;
  stepCount: number;
}

// Max characters of a single tool result preserved in the packet preview.
const TOOL_PREVIEW_LIMIT = 600;
const ASSISTANT_PREVIEW_LIMIT = 1200;

// ─── Session extraction ────────────────────────────────

type SessionLike = {
  getBranch?: () => unknown[];
  getEntries?: () => unknown[];
};

function textFromContent(content: unknown, limit: number): string {
  if (typeof content === "string") return content.slice(0, limit);
  if (!Array.isArray(content)) return "";
  const parts: string[] = [];
  for (const block of content) {
    if (block && typeof block === "object" && (block as { type?: string }).type === "text") {
      parts.push(String((block as { text?: string }).text ?? ""));
    }
  }
  return parts.join("\n").trim().slice(0, limit);
}

/**
 * Extract a normalized trajectory from the live session.
 *
 * Reads message entries from the current branch and flattens pi's
 * AgentMessage content blocks (text / toolCall / toolResult) into compact
 * steps. Defensive about shapes so it degrades gracefully across pi versions.
 */
export function extractTrajectoryFromSession(sessionManager: unknown): {
  steps: TrajectoryStep[];
  model?: string;
  prompt: string;
} {
  const sm = sessionManager as SessionLike;
  const entries: unknown[] =
    (typeof sm?.getBranch === "function" ? sm.getBranch() : undefined) ??
    (typeof sm?.getEntries === "function" ? sm.getEntries() : undefined) ??
    [];

  const steps: TrajectoryStep[] = [];
  let model: string | undefined;
  let prompt = "";

  for (const entry of entries) {
    const e = entry as { type?: string; message?: unknown };
    if (e?.type !== "message" || !e.message) continue;
    const msg = e.message as {
      role?: string;
      content?: unknown;
      model?: string;
      toolName?: string;
      toolCallId?: string;
      isError?: boolean;
    };

    if (msg.role === "user") {
      const text = textFromContent(msg.content, ASSISTANT_PREVIEW_LIMIT);
      if (!prompt && text) prompt = text;
      steps.push({ role: "user", text });
    } else if (msg.role === "assistant") {
      if (!model && msg.model) model = msg.model;
      const toolCalls: TrajectoryStep["tool_calls"] = [];
      if (Array.isArray(msg.content)) {
        for (const block of msg.content) {
          const b = block as {
            type?: string;
            id?: string;
            name?: string;
            arguments?: unknown;
          };
          if (b?.type === "toolCall") {
            toolCalls.push({
              id: String(b.id ?? ""),
              name: String(b.name ?? "unknown"),
              arguments: b.arguments ?? {},
            });
          }
        }
      }
      const text = textFromContent(msg.content, ASSISTANT_PREVIEW_LIMIT);
      const step: TrajectoryStep = { role: "assistant" };
      if (text) step.text = text;
      if (toolCalls.length > 0) step.tool_calls = toolCalls;
      if (step.text || step.tool_calls) steps.push(step);
    } else if (msg.role === "toolResult") {
      steps.push({
        role: "tool",
        tool_call_id: msg.toolCallId ? String(msg.toolCallId) : undefined,
        tool_name: msg.toolName ? String(msg.toolName) : undefined,
        text: textFromContent(msg.content, TOOL_PREVIEW_LIMIT),
        is_error: Boolean(msg.isError),
      });
    }
  }

  return { steps, model, prompt };
}

// ─── Capture ───────────────────────────────────────────

/** Build a human/LLM-readable README summary of a trajectory packet. */
function buildTrajectoryReadme(packet: TrajectoryPacket, title: string): string {
  const toolCalls = packet.steps.flatMap((s) => s.tool_calls ?? []);
  const toolCounts = new Map<string, number>();
  for (const tc of toolCalls) toolCounts.set(tc.name, (toolCounts.get(tc.name) ?? 0) + 1);
  const toolSummary =
    [...toolCounts.entries()]
      .sort((a, b) => b[1] - a[1])
      .map(([name, n]) => `${name}×${n}`)
      .join(", ") || "none";

  const lines: string[] = [
    `# Trajectory ${packet.id}: ${title}`,
    "",
    `- **Captured:** ${packet.captured}`,
    `- **Model:** ${packet.model || "unknown"}`,
    `- **Steps:** ${packet.steps.length}`,
    `- **Tools used:** ${toolSummary}`,
    "",
    "## Task",
    "",
    packet.prompt || "_No prompt recorded._",
    "",
    "## Tool-call sequence",
    "",
  ];

  let i = 1;
  for (const step of packet.steps) {
    if (step.role === "assistant" && step.tool_calls?.length) {
      for (const tc of step.tool_calls) {
        lines.push(`${i}. \`${tc.name}\``);
        i++;
      }
    }
  }
  if (i === 1) lines.push("_No tool calls recorded._");
  lines.push("");

  return lines.join("\n");
}

/**
 * Capture an agent task trajectory into an immutable packet plus a
 * self-contained summary (extracted.md). No `[LLM:]` case skeleton is emitted
 * (issue #80) — case pages, if wanted, are written during distillation via
 * wiki_ensure_page(type='case').
 */
export function captureTrajectory(
  paths: VaultPaths,
  input: CaptureTrajectoryInput,
): CaptureTrajectoryResult {
  assertWritableVault(paths);
  const trajectoryId = nextTrajectoryId(paths);
  const packetPath = join(paths.rawTrajectories, trajectoryId);
  mkdirSync(packetPath, { recursive: true });

  const steps = input.steps ?? [];
  const prompt = input.task?.trim() || steps.find((s) => s.role === "user")?.text?.trim() || "";
  const title =
    input.title?.trim() ||
    (prompt ? prompt.replace(/\s+/g, " ").slice(0, 60) : `Task ${trajectoryId}`);

  const packet: TrajectoryPacket = {
    id: trajectoryId,
    captured: fmtDate(),
    packet_version: "1.0",
    prompt,
    ...(input.model ? { model: input.model } : {}),
    steps,
  };

  // Immutable full trajectory.
  writeJson(join(packetPath, "packet.json"), packet);

  // Lightweight manifest so buildRegistry catalogs it uniformly with sources.
  const toolCallCount = steps.reduce((n, s) => n + (s.tool_calls?.length ?? 0), 0);
  writeJson(join(packetPath, "manifest.json"), {
    id: trajectoryId,
    captured: packet.captured,
    packet_version: "1.0",
    title,
    format: "trajectory",
    model: packet.model || "unknown",
    outcome: input.outcome ?? "success",
    step_count: steps.length,
    tool_call_count: toolCallCount,
  });

  // Self-contained, human/LLM-readable summary — no skeleton to flesh later.
  writeFileSync(join(packetPath, "extracted.md"), buildTrajectoryReadme(packet, title), "utf-8");

  appendEvent(paths, {
    kind: "capture_trajectory",
    trajectory_id: trajectoryId,
    step_count: steps.length,
    tool_call_count: toolCallCount,
  });

  rebuildMetadataLight(paths);

  return {
    trajectoryId,
    packetPath,
    stepCount: steps.length,
  };
}

// ─── Tool: wiki_capture_trajectory ─────────────────────

function vaultMissing() {
  return {
    content: [
      {
        type: "text" as const,
        text: "No wiki vault found at this location. Initialize one with wiki_bootstrap first.",
      },
    ],
    details: { error: "no_vault" } as Record<string, unknown>,
    isError: true,
  };
}

const StepSchema = Type.Object({
  role: Type.Union([Type.Literal("user"), Type.Literal("assistant"), Type.Literal("tool")]),
  text: Type.Optional(Type.String()),
  tool_calls: Type.Optional(
    Type.Array(
      Type.Object({
        id: Type.String(),
        name: Type.String(),
        arguments: Type.Unknown(),
      }),
    ),
  ),
  tool_call_id: Type.Optional(Type.String()),
  tool_name: Type.Optional(Type.String()),
  is_error: Type.Optional(Type.Boolean()),
});

export function registerWikiCaptureTrajectory(pi: ExtensionAPI): void {
  pi.registerTool({
    name: "wiki_capture_trajectory",
    label: "Wiki Capture Trajectory",
    description:
      "Capture the just-completed task's tool-call trajectory into an immutable " +
      "packet plus a skeleton case page. By default the trajectory is extracted " +
      "automatically from the live session; pass `steps` to override. This is the " +
      "working-memory counterpart to wiki_capture_source.",
    promptSnippet: "Record the completed task trajectory into the wiki",
    promptGuidelines: [
      "Use wiki_capture_trajectory after a non-trivial task worth learning from. The extension auto-extracts the tool-call trajectory from the session — you usually only need to pass a title.",
      "Then run wiki_distill_skills to generalize captured trajectories into reusable skill pages.",
    ],
    parameters: Type.Object({
      title: Type.Optional(
        Type.String({ description: "Short descriptive title for the task (≤60 chars)." }),
      ),
      task: Type.Optional(
        Type.String({
          description:
            "The task/prompt that started the work. Inferred from the session if omitted.",
        }),
      ),
      outcome: Type.Optional(
        Type.Union([Type.Literal("success"), Type.Literal("failure"), Type.Literal("partial")], {
          description: "Outcome of the task (default: success).",
        }),
      ),
      steps: Type.Optional(
        Type.Array(StepSchema, {
          description:
            "Explicit trajectory steps (OpenAI-ish tool-call history). Omit to auto-extract from the live session.",
        }),
      ),
      model: Type.Optional(Type.String({ description: "Model that ran the task." })),
    }),
    async execute(_toolCallId, params, _signal, _onUpdate, ctx: ExtensionContext) {
      const paths = resolveVaultPaths(ctx.cwd ?? process.cwd());
      const vaultCheck = inspectWritableVault(paths);
      if (!vaultCheck.ok) {
        return {
          content: [
            { type: "text", text: `Wiki vault error: ${vaultCheck.diagnostics[0].message}` },
          ],
          details: {
            error: vaultCheck.diagnostics[0].code,
            diagnostics: vaultCheck.diagnostics,
          } as Record<string, unknown>,
          isError: true,
        };
      }

      let steps = params.steps as TrajectoryStep[] | undefined;
      let model = params.model;
      let task = params.task;

      if (!steps || steps.length === 0) {
        const extracted = extractTrajectoryFromSession(ctx.sessionManager);
        steps = extracted.steps;
        model = model || extracted.model;
        task = task || extracted.prompt;
      }

      if (!steps || steps.length === 0) {
        return {
          content: [
            {
              type: "text",
              text: "No trajectory could be extracted from the session. Pass `steps` explicitly to capture a trajectory.",
            },
          ],
          details: { error: "empty_trajectory" } as Record<string, unknown>,
          isError: true,
        };
      }

      const result = captureTrajectory(paths, {
        title: params.title,
        task,
        steps,
        model,
        outcome: params.outcome,
      });

      return {
        content: [
          {
            type: "text",
            text: [
              `🧭 **Trajectory captured**: ${result.trajectoryId}`,
              "",
              `- Packet: \`${result.packetPath}/packet.json\``,
              `- Summary: \`${result.packetPath}/extracted.md\``,
              `- Steps: ${result.stepCount}`,
              "",
              "**Next (optional):** run `wiki_distill_skills` to generalize captured trajectories into reusable skill pages.",
            ].join("\n"),
          },
        ],
        details: {
          trajectoryId: result.trajectoryId,
          packetPath: result.packetPath,
          stepCount: result.stepCount,
        } as Record<string, unknown>,
      };
    },
  });
}

// ─── Tool: wiki_distill_skills ─────────────────────────

/** Determine which trajectory IDs have already been cited by a skill page. */
function distilledTrajectoryIds(paths: VaultPaths): Set<string> {
  const backlinks = readJson<Record<string, string[]>>(join(paths.meta, "backlinks.json"), {});
  const distilled = new Set<string>();
  for (const [pageId, inbound] of Object.entries(backlinks)) {
    if (!pageId.startsWith("trajectories/")) continue;
    if (inbound.some((src) => src.startsWith("skills/"))) {
      distilled.add(pageId.split("/").pop() as string);
    }
  }
  return distilled;
}

export function registerWikiDistillSkills(pi: ExtensionAPI): void {
  pi.registerTool({
    name: "wiki_distill_skills",
    label: "Wiki Distill Skills",
    description:
      "Return a batch of captured trajectories (agent working-memory) that have not " +
      "yet been distilled into skill pages. Read each packet and synthesize reusable " +
      "skill pages (and/or refine case pages) that cite the trajectory IDs.",
    promptSnippet: "Distill captured trajectories into reusable skill pages",
    promptGuidelines: [
      "Use wiki_distill_skills to generalize one or more captured trajectories into reusable skill pages via wiki_ensure_page(type='skill').",
      "Every skill page must cite the trajectory IDs it was distilled from with [[trajectories/TRJ-...]] wikilinks.",
    ],
    parameters: Type.Object({
      trajectory_id: Type.Optional(
        Type.String({
          description: "Specific trajectory ID to distill. Omit for all undistilled.",
        }),
      ),
      batch_size: Type.Optional(
        Type.Number({ description: "Max trajectories to return (default: 3, max: 5)", default: 3 }),
      ),
    }),
    async execute(_toolCallId, params, _signal, _onUpdate, ctx: ExtensionContext) {
      const paths = resolveVaultPaths(ctx.cwd ?? process.cwd());
      if (!existsSync(join(paths.dotWiki, "config.json"))) return vaultMissing();

      const batchSize = Math.min(params.batch_size ?? 3, 5);

      if (!existsSync(paths.rawTrajectories)) {
        return {
          content: [
            {
              type: "text",
              text: "No raw/trajectories/ directory. Capture trajectories first with wiki_capture_trajectory.",
            },
          ],
          details: { error: "no_trajectories" } as Record<string, unknown>,
        };
      }

      const packets = readdirSync(paths.rawTrajectories)
        .filter((d) => d.startsWith("TRJ-"))
        .sort();
      const distilled = distilledTrajectoryIds(paths);

      let toProcess = packets.filter((p) => !distilled.has(p));
      if (params.trajectory_id) {
        if (!packets.includes(params.trajectory_id)) {
          return {
            content: [{ type: "text", text: `Trajectory ${params.trajectory_id} not found.` }],
            details: { trajectory_id: params.trajectory_id, status: "not_found" } as Record<
              string,
              unknown
            >,
          };
        }
        toProcess = [params.trajectory_id];
      }

      const batch = toProcess.slice(0, batchSize);
      if (batch.length === 0) {
        return {
          content: [
            {
              type: "text",
              text: "✅ All trajectories distilled. Capture more with wiki_capture_trajectory.",
            },
          ],
          details: { distilled: distilled.size, total: packets.length } as Record<string, unknown>,
        };
      }

      const trajectories = batch.map((id) => {
        const readmePath = join(paths.rawTrajectories, id, "extracted.md");
        const manifestPath = join(paths.rawTrajectories, id, "manifest.json");
        const readme = existsSync(readmePath) ? readFileSync(readmePath, "utf-8") : "";
        const manifest = readJson<Record<string, unknown>>(manifestPath, {});
        return { id, readme, manifest };
      });

      return {
        content: [
          {
            type: "text",
            text: [
              `🧪 **${batch.length} trajectory(ies) ready** (${toProcess.length - batch.length} remaining)`,
              "",
              ...trajectories.map((t) =>
                [
                  `- **${t.id}**: ${t.manifest.title || t.id}`,
                  `  - Tool calls: ${t.manifest.tool_call_count ?? "?"}, steps: ${t.manifest.step_count ?? "?"}`,
                  `  - Packet: \`raw/trajectories/${t.id}/packet.json\``,
                  `  - Summary: \`raw/trajectories/${t.id}/extracted.md\``,
                ].join("\n"),
              ),
              "",
              "**Next steps for each trajectory:**",
              "1. Read packet.json (full tool-call sequence) and extracted.md (summary)",
              "2. Create/refine reusable skill pages via wiki_ensure_page(type='skill')",
              "3. Optionally write a case page (a specific past task) via wiki_ensure_page(type='case')",
              "4. Cite the trajectory with [[trajectories/TRJ-...]] in each skill's 'Distilled From'",
              "",
              "The extension auto-updates metadata when you're done.",
            ].join("\n"),
          },
        ],
        details: {
          batch: trajectories.map((t) => t.id),
          remaining: toProcess.length - batch.length,
        } as Record<string, unknown>,
      };
    },
  });
}

// ─── Tool: wiki_recall_skill ───────────────────────────

export function registerWikiRecallSkill(pi: ExtensionAPI): void {
  pi.registerTool({
    name: "wiki_recall_skill",
    label: "Wiki Recall Skill",
    description:
      "Search distilled skills and past cases (agent working-memory) for patterns " +
      "relevant to the current task — answers 'have I done something like this before?'. " +
      "Filters layered recall to skill and case pages.",
    promptSnippet: "Recall distilled skills and past cases relevant to the task",
    promptGuidelines: [
      "Use wiki_recall_skill at the START of a task to find reusable skills and similar past cases before doing the work.",
    ],
    parameters: Type.Object({
      query: Type.String({ description: "Search query — use the task description or key terms" }),
      kind: Type.Optional(
        Type.Union([Type.Literal("skill"), Type.Literal("case"), Type.Literal("any")], {
          description: "Filter to skills, cases, or both (default: any).",
        }),
      ),
      max_results: Type.Optional(
        Type.Number({ description: "Max results (default: 5, max: 10)", default: 5 }),
      ),
    }),
    async execute(_toolCallId, params, _signal, _onUpdate, ctx: ExtensionContext) {
      const paths = resolveVaultPaths(ctx.cwd ?? process.cwd());
      if (!existsSync(join(paths.dotWiki, "config.json"))) return vaultMissing();

      const maxResults = Math.min(params.max_results ?? 5, 10);
      const kind = params.kind ?? "any";
      // Over-fetch then filter by type, since searchWikiLayered is type-agnostic.
      const raw = searchWikiLayered(paths, params.query, maxResults * 4, 0);
      const wanted = kind === "any" ? ["skill", "case"] : [kind];
      const results = raw.filter((r) => wanted.includes(r.type)).slice(0, maxResults);

      if (results.length === 0) {
        return {
          content: [
            {
              type: "text",
              text: `No ${kind === "any" ? "skills or cases" : `${kind}s`} found matching "${params.query}". Capture work with wiki_capture_trajectory and distill it with wiki_distill_skills.`,
            },
          ],
          details: { query: params.query, kind, matches: [] } as Record<string, unknown>,
        };
      }

      return {
        content: [
          {
            type: "text",
            text: `Found ${results.length} ${kind === "any" ? "skill/case" : kind} page(s) matching "${params.query}":\n\n${results
              .map((r) => {
                const vault = r.vaultLabel ? ` ${r.vaultLabel}` : "";
                return `## [[${r.id}]] — ${r.title}${vault}\nType: ${r.type}\nPath: ${r.path}\n\n${r.preview}`;
              })
              .join("\n\n---\n\n")}`,
          },
        ],
        details: { query: params.query, kind, matches: results } as Record<string, unknown>,
      };
    },
  });
}
