/**
 * file-search — first-class `fd` and `rg` tools for pi.
 *
 * On session start the extension resolves a usable binary for each tool:
 * a normally installed system binary is preferred (silently), then an
 * existing fallback in this repo's `bin/` directory (silently), and only
 * when neither exists is an official release downloaded into `bin/` — the
 * single case that shows a UI notification. Tools await that initialization
 * before executing, and report a clear error if it failed.
 *
 * Supports Linux (x64, arm64), macOS (x64, arm64), and Windows (x64, arm64).
 * Uses HTTPS + SHA256 verification for all downloaded binaries.
 */

import { NodeServices } from "@effect/platform-node";
import type {
  AgentToolResult,
  ExtensionAPI,
  ExtensionContext,
  Theme,
} from "@earendil-works/pi-coding-agent";
import { StringEnum } from "@earendil-works/pi-ai";
import { Text, type Component } from "@earendil-works/pi-tui";
import { Cause, Data, Effect, Exit } from "effect";
import { Type } from "typebox";

import {
  buildFdArgs,
  buildRgArgs,
  FD_MAX_DEPTH_LIMIT,
  FD_MAX_LIMIT,
  RG_MAX_CONTEXT,
  RG_MAX_COUNT_LIMIT,
  type FdToolParams,
  type RgToolParams,
} from "./src/args.ts";
import {
  currentTarget,
  liveBinaryEnv,
  repositoryBinDir,
  resolveBinary,
  TOOL_SPECS,
  type BinaryEnv,
  type BinarySource,
  type PlatformTarget,
  type ResolvedBinary,
} from "./src/binaries.ts";
import { formatCapturedOutput, type CapturedOutput } from "./src/output.ts";
import {
  FD_PARAMETER_DESCRIPTIONS,
  FD_PROMPT_GUIDELINES,
  FD_PROMPT_SNIPPET,
  FD_TOOL_DESCRIPTION,
  RG_PARAMETER_DESCRIPTIONS,
  RG_PROMPT_GUIDELINES,
  RG_PROMPT_SNIPPET,
  RG_TOOL_DESCRIPTION,
} from "./src/prompt.ts";
import { discardCapturedOutput, executeSearchProcess } from "./src/process.ts";

// ---------------------------------------------------------------------------
// Binary initialization
// ---------------------------------------------------------------------------

export function makeBinaryInitializers(
  binDir: string,
  target: PlatformTarget,
  env: BinaryEnv,
) {
  return {
    fd: Effect.runSync(
      Effect.cached(resolveBinary(TOOL_SPECS.fd, binDir, target, env)),
    ),
    rg: Effect.runSync(
      Effect.cached(resolveBinary(TOOL_SPECS.rg, binDir, target, env)),
    ),
  };
}

/**
 * Human-readable install notice, shown only for fresh downloads.
 */
export function installNotifications(
  binaries: readonly ResolvedBinary[],
): string[] {
  return binaries
    .filter((binary) => binary.source === "installed")
    .map(
      (binary) =>
        `file-search: no system ${binary.tool} found — downloaded ${binary.tool} ${binary.version ?? ""} to ${repositoryBinDir()}`.trimEnd(),
    );
}

// ---------------------------------------------------------------------------
// Errors
// ---------------------------------------------------------------------------

class SearchError extends Data.TaggedError("SearchError")<{
  readonly message: string;
}> {}

interface SearchOutcome {
  readonly output: CapturedOutput;
  readonly noMatches: boolean;
  readonly binarySource: BinarySource;
}

// ---------------------------------------------------------------------------
// Tool detail types
// ---------------------------------------------------------------------------

export interface FdToolDetails {
  readonly binarySource: BinarySource;
  readonly matchCount: number;
  readonly truncated: boolean;
  readonly fullOutputPath?: string;
}

export interface RgToolDetails {
  readonly binarySource: BinarySource;
  readonly outputLines: number;
  readonly truncated: boolean;
  readonly fullOutputPath?: string;
}

// ---------------------------------------------------------------------------
// Execution
// ---------------------------------------------------------------------------

const EXEC_TIMEOUT_MS = 60_000;

function causeMessage(cause: Cause.Cause<unknown>): string {
  const [first] = Cause.prettyErrors(cause);
  return first?.message ?? Cause.pretty(cause);
}

function unwrapToolExit<T>(
  exit: Exit.Exit<T, SearchError>,
  tool: "fd" | "rg",
): T {
  if (Exit.isSuccess(exit)) return exit.value;
  if (Cause.hasInterruptsOnly(exit.cause)) {
    throw new Error(`${tool} search was cancelled.`);
  }
  throw new Error(causeMessage(exit.cause));
}

// ---------------------------------------------------------------------------
// Main extension
// ---------------------------------------------------------------------------

export default function fileSearchTools(pi: ExtensionAPI) {
  let notified = false;

  const binDir = repositoryBinDir();
  const target = currentTarget();
  const initializers = makeBinaryInitializers(binDir, target, liveBinaryEnv);

  pi.on("session_start", async (_event, ctx) => {
    const exit = await Effect.runPromiseExit(
      Effect.gen(function* () {
        const initialized = yield* Effect.all(
          {
            fd: Effect.exit(initializers.fd),
            rg: Effect.exit(initializers.rg),
          },
          { concurrency: "unbounded" },
        );

        if (!ctx.hasUI || notified) return;
        notified = true;

        for (const tool of ["fd", "rg"] as const) {
          const toolExit = initialized[tool];
          if (Exit.isSuccess(toolExit)) {
            for (const message of installNotifications([toolExit.value])) {
              ctx.ui.notify(message, "info");
            }
          } else {
            ctx.ui.notify(
              `file-search ${tool} setup failed: ${causeMessage(toolExit.cause)}`,
              "error",
            );
          }
        }
      }),
    );

    if (Exit.isFailure(exit) && ctx.hasUI && !notified) {
      notified = true;
      ctx.ui.notify(
        `file-search setup failed: ${causeMessage(exit.cause)}`,
        "error",
      );
    }
  });

  /**
   * Await init, stream the binary output to disk, and classify its exit.
   */
  function runSearch(
    tool: "fd" | "rg",
    args: string[],
    ctx: ExtensionContext,
  ): Effect.Effect<SearchOutcome, SearchError> {
    return Effect.gen(function* () {
      const binary = yield* initializers[tool];
      const result = yield* executeSearchProcess({
        command: binary.command,
        args,
        cwd: ctx.cwd,
        tempPrefix: `pi-${tool}-`,
      });

      // ripgrep exits 1 for "no matches"; fd exits 0 even with no results.
      if (
        tool === "rg" &&
        result.code === 1 &&
        result.output.lineCount === 0
      ) {
        return {
          output: result.output,
          noMatches: true,
          binarySource: binary.source,
        } satisfies SearchOutcome;
      }

      if (result.code !== 0) {
        yield* discardCapturedOutput(result.output);
        const detail = result.stderr.trim() || `exit code ${result.code}`;
        return yield* new SearchError({
          message: `${tool} failed: ${detail}`,
        });
      }

      return {
        output: result.output,
        noMatches: result.output.lineCount === 0,
        binarySource: binary.source,
      } satisfies SearchOutcome;
    }).pipe(
      Effect.timeout(EXEC_TIMEOUT_MS),
      Effect.mapError((error) => {
        if (error instanceof SearchError) return error;
        return new SearchError({
          message:
            (error as { _tag?: string })._tag === "TimeoutError"
              ? `${tool} timed out.`
              : error instanceof Error
                ? error.message
                : String(error),
        });
      }),
      Effect.provide(NodeServices.layer),
    );
  }

  // -----------------------------------------------------------------------
  // fd tool
  // -----------------------------------------------------------------------

  const fdSchema = Type.Object({
    pattern: Type.Optional(
      Type.String({ description: FD_PARAMETER_DESCRIPTIONS.pattern }),
    ),
    path: Type.Optional(
      Type.String({ description: FD_PARAMETER_DESCRIPTIONS.path }),
    ),
    type: Type.Optional(
      StringEnum(["file", "directory", "symlink"] as const, {
        description: FD_PARAMETER_DESCRIPTIONS.type,
      }),
    ),
    extension: Type.Optional(
      Type.String({ description: FD_PARAMETER_DESCRIPTIONS.extension }),
    ),
    glob: Type.Optional(
      Type.Boolean({ description: FD_PARAMETER_DESCRIPTIONS.glob }),
    ),
    hidden: Type.Optional(
      Type.Boolean({ description: FD_PARAMETER_DESCRIPTIONS.hidden }),
    ),
    max_depth: Type.Optional(
      Type.Integer({
        description: FD_PARAMETER_DESCRIPTIONS.max_depth,
        minimum: 1,
        maximum: FD_MAX_DEPTH_LIMIT,
      }),
    ),
    limit: Type.Optional(
      Type.Integer({
        description: FD_PARAMETER_DESCRIPTIONS.limit,
        minimum: 1,
        maximum: FD_MAX_LIMIT,
      }),
    ),
  });

  pi.registerTool({
    name: "fd",
    label: "Find Files",
    description: FD_TOOL_DESCRIPTION,
    promptSnippet: FD_PROMPT_SNIPPET,
    promptGuidelines: FD_PROMPT_GUIDELINES,
    parameters: fdSchema,

    async execute(
      _toolCallId: string,
      params: FdToolParams,
      signal: AbortSignal | undefined,
      _onUpdate,
      ctx: ExtensionContext,
    ): Promise<AgentToolResult<FdToolDetails>> {
      const exit = await Effect.runPromiseExit(
        Effect.gen(function* () {
          const outcome = yield* runSearch("fd", buildFdArgs(params), ctx);

          if (outcome.noMatches) {
            return {
              content: [{ type: "text" as const, text: "No files found" }],
              details: {
                binarySource: outcome.binarySource,
                matchCount: 0,
                truncated: false,
              } satisfies FdToolDetails,
            };
          }

          const formatted = formatCapturedOutput(outcome.output);
          return {
            content: [{ type: "text" as const, text: formatted.text }],
            details: {
              binarySource: outcome.binarySource,
              matchCount: formatted.lineCount,
              truncated: formatted.truncated,
              fullOutputPath: formatted.fullOutputPath,
            } satisfies FdToolDetails,
          };
        }),
        signal ? { signal } : undefined,
      );

      return unwrapToolExit(exit, "fd");
    },

    renderCall(
      args: FdToolParams,
      theme: Theme,
      _context,
    ): Component {
      let text = theme.fg("toolTitle", theme.bold("fd "));
      text += theme.fg(
        "accent",
        args.pattern ? `"${args.pattern}"` : "(all)",
      );
      if (args.path) text += theme.fg("muted", ` in ${args.path}`);

      const flags = [
        args.type && `type=${args.type}`,
        args.extension && `ext=${args.extension}`,
        args.glob && "glob",
        args.hidden && "hidden",
        args.max_depth !== undefined && `depth≤${args.max_depth}`,
      ].filter((flag): flag is string => typeof flag === "string");

      if (flags.length > 0) text += " " + theme.fg("dim", flags.join(" "));
      return new Text(text, 0, 0);
    },

    renderResult(
      result: AgentToolResult<FdToolDetails>,
      { expanded, isPartial }: { expanded: boolean; isPartial: boolean },
      theme: Theme,
      _context,
    ): Component {
      if (isPartial)
        return new Text(theme.fg("warning", "Searching..."), 0, 0);

      const details = result.details;
      if (!details || details.matchCount === 0) {
        return new Text(theme.fg("dim", "No files found"), 0, 0);
      }

      let text = theme.fg(
        "success",
        `${details.matchCount} ${details.matchCount === 1 ? "entry" : "entries"}`,
      );
      if (details.truncated) text += theme.fg("warning", " (truncated)");
      if (expanded)
        text += expandedPreview(result, details.fullOutputPath, theme);
      return new Text(text, 0, 0);
    },
  });

  // -----------------------------------------------------------------------
  // rg tool
  // -----------------------------------------------------------------------

  const rgSchema = Type.Object({
    pattern: Type.String({ description: RG_PARAMETER_DESCRIPTIONS.pattern }),
    path: Type.Optional(
      Type.String({ description: RG_PARAMETER_DESCRIPTIONS.path }),
    ),
    glob: Type.Optional(
      Type.String({ description: RG_PARAMETER_DESCRIPTIONS.glob }),
    ),
    file_type: Type.Optional(
      Type.String({ description: RG_PARAMETER_DESCRIPTIONS.file_type }),
    ),
    case_sensitive: Type.Optional(
      Type.Boolean({ description: RG_PARAMETER_DESCRIPTIONS.case_sensitive }),
    ),
    fixed_strings: Type.Optional(
      Type.Boolean({ description: RG_PARAMETER_DESCRIPTIONS.fixed_strings }),
    ),
    hidden: Type.Optional(
      Type.Boolean({ description: RG_PARAMETER_DESCRIPTIONS.hidden }),
    ),
    context: Type.Optional(
      Type.Integer({
        description: RG_PARAMETER_DESCRIPTIONS.context,
        minimum: 0,
        maximum: RG_MAX_CONTEXT,
      }),
    ),
    limit: Type.Optional(
      Type.Integer({
        description: RG_PARAMETER_DESCRIPTIONS.limit,
        minimum: 1,
        maximum: RG_MAX_COUNT_LIMIT,
      }),
    ),
  });

  pi.registerTool({
    name: "rg",
    label: "Search Content",
    description: RG_TOOL_DESCRIPTION,
    promptSnippet: RG_PROMPT_SNIPPET,
    promptGuidelines: RG_PROMPT_GUIDELINES,
    parameters: rgSchema,

    async execute(
      _toolCallId: string,
      params: RgToolParams,
      signal: AbortSignal | undefined,
      _onUpdate,
      ctx: ExtensionContext,
    ): Promise<AgentToolResult<RgToolDetails>> {
      const exit = await Effect.runPromiseExit(
        Effect.gen(function* () {
          const outcome = yield* runSearch("rg", buildRgArgs(params), ctx);

          if (outcome.noMatches) {
            return {
              content: [{ type: "text" as const, text: "No matches found" }],
              details: {
                binarySource: outcome.binarySource,
                outputLines: 0,
                truncated: false,
              } satisfies RgToolDetails,
            };
          }

          const formatted = formatCapturedOutput(outcome.output);
          return {
            content: [{ type: "text" as const, text: formatted.text }],
            details: {
              binarySource: outcome.binarySource,
              outputLines: formatted.lineCount,
              truncated: formatted.truncated,
              fullOutputPath: formatted.fullOutputPath,
            } satisfies RgToolDetails,
          };
        }),
        signal ? { signal } : undefined,
      );

      return unwrapToolExit(exit, "rg");
    },

    renderCall(
      args: RgToolParams,
      theme: Theme,
      _context,
    ): Component {
      let text = theme.fg("toolTitle", theme.bold("rg "));
      text += theme.fg("accent", `"${args.pattern}"`);
      if (args.path) text += theme.fg("muted", ` in ${args.path}`);

      const flags = [
        args.glob && `glob=${args.glob}`,
        args.file_type && `type=${args.file_type}`,
        args.fixed_strings && "literal",
        args.hidden && "hidden",
        args.context !== undefined && `ctx=${args.context}`,
      ].filter((flag): flag is string => typeof flag === "string");

      if (flags.length > 0) text += " " + theme.fg("dim", flags.join(" "));
      return new Text(text, 0, 0);
    },

    renderResult(
      result: AgentToolResult<RgToolDetails>,
      { expanded, isPartial }: { expanded: boolean; isPartial: boolean },
      theme: Theme,
      _context,
    ): Component {
      if (isPartial)
        return new Text(theme.fg("warning", "Searching..."), 0, 0);

      const details = result.details;
      if (!details || details.outputLines === 0) {
        return new Text(theme.fg("dim", "No matches found"), 0, 0);
      }

      let text = theme.fg(
        "success",
        `${details.outputLines} output ${details.outputLines === 1 ? "line" : "lines"}`,
      );
      if (details.truncated) text += theme.fg("warning", " (truncated)");
      if (expanded)
        text += expandedPreview(result, details.fullOutputPath, theme);
      return new Text(text, 0, 0);
    },
  });
}

// ---------------------------------------------------------------------------
// Render helpers
// ---------------------------------------------------------------------------

const PREVIEW_LINES = 20;

interface ThemeLike {
  fg(color: string, text: string): string;
}

function expandedPreview(
  result: { content: { type: string; text?: string }[] },
  fullOutputPath: string | undefined,
  theme: ThemeLike,
): string {
  let text = "";
  const content = result.content[0];
  if (content?.type === "text" && content.text) {
    const lines = content.text.split("\n");
    for (const line of lines.slice(0, PREVIEW_LINES)) {
      text += `\n${theme.fg("dim", line)}`;
    }
    if (lines.length > PREVIEW_LINES) {
      text += `\n${theme.fg("muted", `... ${lines.length - PREVIEW_LINES} more lines`)}`;
    }
  }
  if (fullOutputPath) {
    text += `\n${theme.fg("dim", `Full output: ${fullOutputPath}`)}`;
  }
  return text;
}