/**
 * Files Extension
 *
 * /files command lists all files the model has read/written/edited in the active session branch,
 * coalesced by path and sorted newest first. Selecting a file opens it in VS Code.
 */

import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
import { DynamicBorder } from "@mariozechner/pi-coding-agent";
import {
  Container,
  Key,
  matchesKey,
  type SelectItem,
  SelectList,
  Text,
} from "@mariozechner/pi-tui";

interface FileEntry {
  path: string;
  operations: Set<"read" | "write" | "edit">;
  lastTimestamp: number;
}

type FileToolName = "read" | "write" | "edit";

export default function (pi: ExtensionAPI) {
  pi.registerCommand("files", {
    description: "Show files read/written/edited in this session",
    handler: async (_args, ctx) => {
      if (!ctx.hasUI) {
        ctx.ui.notify("No UI available", "error");
        return;
      }

      // Get the current branch (path from leaf to root)
      const branch = ctx.sessionManager.getBranch();

      // First pass: collect tool calls (id -> {path, name}) from assistant messages
      const toolCalls = new Map<string, { path: string; name: FileToolName; timestamp: number }>();

      for (const entry of branch) {
        if (entry.type !== "message") continue;
        const msg = entry.message;

        if (msg.role === "assistant" && Array.isArray(msg.content)) {
          for (const block of msg.content) {
            if (block.type === "toolCall") {
              const name = block.name;
              if (name === "read" || name === "write" || name === "edit") {
                const path = block.arguments?.path;
                if (path && typeof path === "string") {
                  toolCalls.set(block.id, { path, name, timestamp: msg.timestamp });
                }
              }
            }
          }
        }
      }

      // Second pass: match tool results to get the actual execution timestamp
      const fileMap = new Map<string, FileEntry>();

      for (const entry of branch) {
        if (entry.type !== "message") continue;
        const msg = entry.message;

        if (msg.role === "toolResult") {
          const toolCall = toolCalls.get(msg.toolCallId);
          if (!toolCall) continue;

          const { path, name } = toolCall;
          const timestamp = msg.timestamp;

          const existing = fileMap.get(path);
          if (existing) {
            existing.operations.add(name);
            if (timestamp > existing.lastTimestamp) {
              existing.lastTimestamp = timestamp;
            }
          } else {
            fileMap.set(path, {
              path,
              operations: new Set([name]),
              lastTimestamp: timestamp,
            });
          }
        }
      }

      if (fileMap.size === 0) {
        ctx.ui.notify("No files read/written/edited in this session", "info");
        return;
      }

      // Sort by most recent first
      const files = Array.from(fileMap.values()).sort((a, b) => b.lastTimestamp - a.lastTimestamp);

      const openSelected = async (file: FileEntry): Promise<void> => {
        try {
          await pi.exec("code", ["-g", file.path], { cwd: ctx.cwd });
        } catch (error) {
          const message = error instanceof Error ? error.message : String(error);
          ctx.ui.notify(`Failed to open ${file.path}: ${message}`, "error");
        }
      };

      // Show file picker with SelectList
      await ctx.ui.custom<void>((tui, theme, _kb, done) => {
        const container = new Container();

        // Top border
        container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));

        // Title
        container.addChild(new Text(theme.fg("accent", theme.bold(" Select file to open")), 0, 0));

        // Build select items with colored operations
        const items: SelectItem[] = files.map((f) => {
          const ops: string[] = [];
          if (f.operations.has("read")) ops.push(theme.fg("muted", "R"));
          if (f.operations.has("write")) ops.push(theme.fg("success", "W"));
          if (f.operations.has("edit")) ops.push(theme.fg("warning", "E"));
          const opsLabel = ops.join("");
          return {
            value: f,
            label: `${opsLabel} ${f.path}`,
          };
        });

        const visibleRows = Math.min(files.length, 15);
        let currentIndex = 0;

        const selectList = new SelectList(items, visibleRows, {
          selectedPrefix: (t) => theme.fg("accent", t),
          selectedText: (t) => t, // Keep existing colors
          description: (t) => theme.fg("muted", t),
          scrollInfo: (t) => theme.fg("dim", t),
          noMatch: (t) => theme.fg("warning", t),
        });
        selectList.onSelect = (item) => {
          void openSelected(item.value as FileEntry);
        };
        selectList.onCancel = () => done();
        selectList.onSelectionChange = (item) => {
          currentIndex = items.indexOf(item);
        };
        container.addChild(selectList);

        // Help text
        container.addChild(
          new Text(theme.fg("dim", " ↑↓ navigate • ←→ page • enter open • esc close"), 0, 0),
        );

        // Bottom border
        container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));

        return {
          render: (w) => container.render(w),
          invalidate: () => container.invalidate(),
          handleInput: (data) => {
            // Add paging with left/right
            if (matchesKey(data, Key.left)) {
              // Page up - clamp to 0
              currentIndex = Math.max(0, currentIndex - visibleRows);
              selectList.setSelectedIndex(currentIndex);
            } else if (matchesKey(data, Key.right)) {
              // Page down - clamp to last
              currentIndex = Math.min(items.length - 1, currentIndex + visibleRows);
              selectList.setSelectedIndex(currentIndex);
            } else {
              selectList.handleInput(data);
            }
            tui.requestRender();
          },
        };
      });
    },
  });
}