import type { AgentToolResult, ToolRenderResultOptions } from '@earendil-works/pi-coding-agent';
import { type Component, Text } from '@earendil-works/pi-tui';

type McpToolResultDetails = Record<string, unknown> & { error?: unknown };
type McpToolContentBlock = AgentToolResult<McpToolResultDetails>['content'][number];

interface RenderTheme {
  fg: (name: string, text: string) => string;
  bold?: (text: string) => string;
}

const plainTheme: RenderTheme = { fg: (_name, text) => text };

export interface McpProxyToolCallInput {
  tool?: string;
  args?: string | Record<string, unknown>;
  connect?: string;
  describe?: string;
  search?: string;
  regex?: boolean;
  includeSchemas?: boolean;
  server?: string;
  action?: string;
}

interface McpToolRenderContext {
  isError: boolean;
}

export interface McpToolResultDisplay {
  lines: string[];
  truncated: boolean;
}

const DEFAULT_MAX_CALL_INPUT_CHARS = 1500;
const DEFAULT_MAX_COLLAPSED_LINES = 3;
const DEFAULT_MAX_COLLAPSED_CHARS = 8000;
const COLLAPSED_RENDER_CHAR_SLACK = 8;

class CollapsibleText implements Component {
  private readonly fullText: Text;
  private readonly footerText: Text;
  private collapsedText: { charBudget: number; fullyIncluded: boolean; text: Text } | null = null;

  constructor(
    private readonly text: string,
    private readonly expanded: boolean,
    private readonly maxCollapsedLines: number,
    ellipsis: string,
    expandHint: string,
    private readonly preTruncated = false
  ) {
    this.fullText = new Text(text, 0, 0);
    this.footerText = new Text(`${ellipsis}\n${expandHint}`, 0, 0);
  }

  render(width: number): string[] {
    if (this.expanded) {
      return this.fullText.render(width);
    }

    const safeWidth = Math.max(1, Math.floor(width));
    const charBudget = safeWidth * (this.maxCollapsedLines + 1) * COLLAPSED_RENDER_CHAR_SLACK;

    if (!this.collapsedText || this.collapsedText.charBudget !== charBudget) {
      const prefix = this.text.length > charBudget ? this.text.slice(0, charBudget) : this.text;

      this.collapsedText = {
        charBudget,
        fullyIncluded: prefix === this.text,
        text: new Text(prefix, 0, 0),
      };
    }

    const lines = this.collapsedText.text.render(width);

    if (!this.preTruncated && this.collapsedText.fullyIncluded && lines.length <= this.maxCollapsedLines) {
      return lines;
    }

    return [...lines.slice(0, this.maxCollapsedLines), ...this.footerText.render(width)];
  }

  invalidate(): void {}
}

function truncateText(value: string, maxChars: number): string {
  if (value.length <= maxChars) {
    return value;
  }

  return `${value.slice(0, Math.max(0, maxChars - 1))}…`;
}

function formatJsonish(value: unknown, maxChars: number): string {
  if (typeof value === 'string') {
    try {
      return truncateText(JSON.stringify(JSON.parse(value), null, 2), maxChars);
    } catch {
      return truncateText(value, maxChars);
    }
  }

  try {
    return truncateText(JSON.stringify(value, null, 2), maxChars);
  } catch {
    return truncateText(String(value), maxChars);
  }
}

function hasUsefulObjectContent(value: unknown): boolean {
  return typeof value === 'object' && value !== null && !Array.isArray(value) && Object.keys(value).length > 0;
}

export function formatMcpProxyToolCallLines(
  args: McpProxyToolCallInput,
  maxInputChars = DEFAULT_MAX_CALL_INPUT_CHARS
): string[] {
  if (args.action === 'ui-messages') {
    return [`mcp ${args.action}`];
  }

  if (args.tool) {
    const target = args.server ? `${args.tool} @ ${args.server}` : args.tool;
    const lines = [`mcp call ${target}`];

    if (args.args) {
      lines.push(formatJsonish(args.args, maxInputChars));
    }

    return lines;
  }

  if (args.connect) {
    return [`mcp connect ${args.connect}`];
  }

  if (args.describe) {
    return [`mcp describe ${args.describe}`];
  }

  if (args.search) {
    let line = `mcp search ${args.search}`;

    if (args.server) {
      line += ` @ ${args.server}`;
    }

    if (args.regex === true) {
      line += ' (regex)';
    }

    if (args.includeSchemas === false) {
      line += ' (schemas hidden)';
    }

    return [line];
  }

  if (args.server) {
    return [`mcp list ${args.server}`];
  }

  if (args.action) {
    return [`mcp ${args.action}`];
  }

  return ['mcp status'];
}

export function formatMcpDirectToolCallLines(
  displayName: string,
  args: Record<string, unknown>,
  maxInputChars = DEFAULT_MAX_CALL_INPUT_CHARS
): string[] {
  if (!hasUsefulObjectContent(args)) {
    return [displayName];
  }

  return [displayName, formatJsonish(args, maxInputChars)];
}

function renderToolCallLines(lines: string[], theme?: RenderTheme) {
  const activeTheme = theme ?? plainTheme;
  const [title = 'mcp', ...rest] = lines;
  const styledTitle = activeTheme.fg('toolTitle', activeTheme.bold ? activeTheme.bold(title) : title);
  const styledRest = rest.map((line) => activeTheme.fg('muted', line));

  return new Text([styledTitle, ...styledRest].join('\n'), 0, 0);
}

export function renderMcpProxyToolCall(args: McpProxyToolCallInput, theme?: RenderTheme) {
  return renderToolCallLines(formatMcpProxyToolCallLines(args), theme);
}

export function createMcpDirectToolCallRenderer(displayName: string) {
  return (args: Record<string, unknown>, theme?: RenderTheme) => {
    return renderToolCallLines(formatMcpDirectToolCallLines(displayName, args), theme);
  };
}

function blockToLines(block: McpToolContentBlock): string[] {
  if (block.type === 'text') {
    return block.text.split('\n');
  }

  return [`[image: ${block.mimeType}]`];
}

function collectCollapsedResultLines(
  content: AgentToolResult<McpToolResultDetails>['content'],
  maxLines: number,
  maxChars: number
): McpToolResultDisplay {
  if (content.length === 0) {
    return { lines: ['(empty result)'], truncated: false };
  }

  const lines: string[] = [];
  let remainingChars = maxChars;
  let truncated = false;

  const appendLine = (line: string) => {
    if (lines.length >= maxLines || remainingChars <= 0) {
      truncated = true;

      return false;
    }

    if (line.length > remainingChars) {
      lines.push(line.slice(0, remainingChars));
      truncated = true;
      remainingChars = 0;

      return false;
    }

    lines.push(line);
    remainingChars -= line.length + 1;

    return true;
  };

  for (const block of content) {
    if (block.type !== 'text') {
      if (!appendLine(`[image: ${block.mimeType}]`)) {
        break;
      }

      continue;
    }

    let start = 0;

    while (start <= block.text.length) {
      const newline = block.text.indexOf('\n', start);
      const line = newline === -1 ? block.text.slice(start) : block.text.slice(start, newline);

      if (!appendLine(line)) {
        break;
      }

      if (newline === -1) {
        break;
      }

      start = newline + 1;
    }

    if (truncated) {
      break;
    }
  }

  if (lines.length === 0) {
    lines.push('');
  }

  if (truncated && lines.length >= maxLines) {
    lines.push('...');
  }

  return { lines, truncated };
}

export function formatMcpToolResultIdentity(details: McpToolResultDetails | undefined): string | null {
  if (details?.mode !== 'call') {
    return null;
  }

  const server =
    typeof details.server === 'string'
      ? details.server
      : typeof details.hintServer === 'string'
        ? details.hintServer
        : null;

  if (!server) {
    return null;
  }

  if (typeof details.tool === 'string') {
    return `MCP ${server}/${details.tool}`;
  }

  if (typeof details.resourceUri === 'string') {
    return `MCP ${server} resource ${details.resourceUri}`;
  }

  if (typeof details.requestedTool === 'string') {
    return `MCP ${server}/${details.requestedTool}`;
  }

  return null;
}

export function formatMcpToolResultLines(
  result: Pick<AgentToolResult<McpToolResultDetails>, 'content'>,
  expanded: boolean,
  maxCollapsedLines = 3,
  maxCollapsedChars = DEFAULT_MAX_COLLAPSED_CHARS
): McpToolResultDisplay {
  if (!expanded) {
    return collectCollapsedResultLines(result.content, maxCollapsedLines, maxCollapsedChars);
  }

  const allLines = result.content.flatMap(blockToLines);
  const lines = allLines.length > 0 ? allLines : ['(empty result)'];

  return { lines, truncated: false };
}

export function renderMcpToolResult(
  result: AgentToolResult<McpToolResultDetails>,
  options: ToolRenderResultOptions,
  theme?: RenderTheme,
  context?: McpToolRenderContext
) {
  const activeTheme = theme ?? plainTheme;

  if (options.isPartial) {
    return new Text(activeTheme.fg('warning', 'Running MCP tool...'), 0, 0);
  }

  const hasErrorDetails = Boolean(result.details.error);
  const expanded = options.expanded || context?.isError === true || hasErrorDetails;
  const display = formatMcpToolResultLines(result, expanded);
  const identity = formatMcpToolResultIdentity(result.details);
  const output = [
    ...(identity ? [activeTheme.fg('muted', identity)] : []),
    ...display.lines.map((line) => activeTheme.fg('toolOutput', line)),
  ].join('\n');

  return new CollapsibleText(
    output,
    expanded,
    DEFAULT_MAX_COLLAPSED_LINES + (identity ? 1 : 0),
    activeTheme.fg('muted', '...'),
    activeTheme.fg('muted', '(Ctrl+O to expand)'),
    display.truncated
  );
}