package main

import (
	"context"
	"encoding/json"

	"github.com/mark3labs/mcp-go/mcp"
	"github.com/mark3labs/mcp-go/server"

	"fn-registry/functions/browser"
)

// registerFrameTools wires frame_list + frame_get_html (read) and frame_eval (MUTA).
func registerFrameTools(s *server.MCPServer, d *deps) {
	s.AddTool(frameListTool(), mcp.NewTypedToolHandler(d.handleFrameList))
	s.AddTool(frameGetHTMLTool(), mcp.NewTypedToolHandler(d.handleFrameGetHTML))

	if !d.readOnly {
		s.AddTool(frameEvalTool(), mcp.NewTypedToolHandler(d.handleFrameEval))
	}
}

// ---- frame_list ----

type frameListArgs struct {
	Port int `json:"port"`
}

func frameListTool() mcp.Tool {
	return mcp.NewTool("frame_list",
		mcp.WithDescription("List all frames (including iframes) of the current page via Page.getFrameTree. Returns JSON with frame IDs."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
	)
}

func (d *deps) handleFrameList(_ context.Context, _ mcp.CallToolRequest, a frameListArgs) (*mcp.CallToolResult, error) {
	var frames []browser.CdpFrame
	err := d.withConn(portOr(a.Port), func(c *browser.CDPConn) error {
		var e error
		frames, e = browser.CdpListFrames(c)
		return e
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	b, _ := json.MarshalIndent(frames, "", "  ")
	return mcp.NewToolResultText(string(b)), nil
}

// ---- frame_eval (MUTA) ----

type frameEvalArgs struct {
	Port       int    `json:"port"`
	FrameID    string `json:"frame_id"`
	Expression string `json:"expression"`
}

func frameEvalTool() mcp.Tool {
	return mcp.NewTool("frame_eval",
		mcp.WithDescription("Evaluate a JavaScript expression inside a specific frame's execution context. Returns the stringified result."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
		mcp.WithString("frame_id", mcp.Required(), mcp.Description("Frame ID (from frame_list).")),
		mcp.WithString("expression", mcp.Required(), mcp.Description("JavaScript expression to evaluate.")),
	)
}

func (d *deps) handleFrameEval(_ context.Context, _ mcp.CallToolRequest, a frameEvalArgs) (*mcp.CallToolResult, error) {
	if a.FrameID == "" {
		return mcp.NewToolResultError("frame_id is required"), nil
	}
	if a.Expression == "" {
		return mcp.NewToolResultError("expression is required"), nil
	}
	var res string
	err := d.withConn(portOr(a.Port), func(c *browser.CDPConn) error {
		var e error
		res, e = browser.CdpEvalInFrame(c, a.FrameID, a.Expression)
		return e
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	return mcp.NewToolResultText(truncate(res, htmlMax)), nil
}

// ---- frame_get_html ----

type frameGetHTMLArgs struct {
	Port    int    `json:"port"`
	FrameID string `json:"frame_id"`
}

func frameGetHTMLTool() mcp.Tool {
	return mcp.NewTool("frame_get_html",
		mcp.WithDescription("Return the serialized HTML of a specific frame. Truncated to 200000 chars."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
		mcp.WithString("frame_id", mcp.Required(), mcp.Description("Frame ID (from frame_list).")),
	)
}

func (d *deps) handleFrameGetHTML(_ context.Context, _ mcp.CallToolRequest, a frameGetHTMLArgs) (*mcp.CallToolResult, error) {
	if a.FrameID == "" {
		return mcp.NewToolResultError("frame_id is required"), nil
	}
	var html string
	err := d.withConn(portOr(a.Port), func(c *browser.CDPConn) error {
		var e error
		html, e = browser.CdpGetFrameHTML(c, a.FrameID)
		return e
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	return mcp.NewToolResultText(truncate(html, htmlMax)), nil
}