package main

import (
	"context"

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

	"fn-registry/functions/browser"
)

const htmlMax = 200_000

// registerReadTools wires page_get_html, page_eval_js (MUTA), page_screenshot.
func registerReadTools(s *server.MCPServer, d *deps) {
	s.AddTool(pageGetHTMLTool(), mcp.NewTypedToolHandler(d.handlePageGetHTML))
	s.AddTool(pageScreenshotTool(), mcp.NewTypedToolHandler(d.handlePageScreenshot))

	if !d.readOnly {
		s.AddTool(pageEvalJSTool(), mcp.NewTypedToolHandler(d.handlePageEvalJS))
	}
}

// ---- page_get_html ----

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

func pageGetHTMLTool() mcp.Tool {
	return mcp.NewTool("page_get_html",
		mcp.WithDescription("Return the current page's full serialized HTML (outerHTML). Truncated to 200000 chars."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
	)
}

func (d *deps) handlePageGetHTML(_ context.Context, _ mcp.CallToolRequest, a pageGetHTMLArgs) (*mcp.CallToolResult, error) {
	var html string
	err := d.withConn(portOr(a.Port), func(c *browser.CDPConn) error {
		var e error
		html, e = browser.CdpGetHTML(c)
		return e
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	return mcp.NewToolResultText(truncate(html, htmlMax)), nil
}

// ---- page_eval_js (MUTA) ----

type pageEvalJSArgs struct {
	Port       int    `json:"port"`
	Expression string `json:"expression"`
}

func pageEvalJSTool() mcp.Tool {
	return mcp.NewTool("page_eval_js",
		mcp.WithDescription("Evaluate a JavaScript expression in the page context via Runtime.evaluate. Returns the stringified result."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
		mcp.WithString("expression", mcp.Required(), mcp.Description("JavaScript expression to evaluate.")),
	)
}

func (d *deps) handlePageEvalJS(_ context.Context, _ mcp.CallToolRequest, a pageEvalJSArgs) (*mcp.CallToolResult, error) {
	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.CdpEvaluate(c, a.Expression)
		return e
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	return mcp.NewToolResultText(truncate(res, htmlMax)), nil
}

// ---- page_screenshot ----

type pageScreenshotArgs struct {
	Port     int    `json:"port"`
	Path     string `json:"path"`
	FullPage bool   `json:"full_page"`
}

func pageScreenshotTool() mcp.Tool {
	return mcp.NewTool("page_screenshot",
		mcp.WithDescription("Capture a screenshot of the current page and write it to a local path (.png/.jpg)."),
		mcp.WithNumber("port", mcp.Description("CDP port. Default 9222.")),
		mcp.WithString("path", mcp.Required(), mcp.Description("Output file path (.png or .jpg).")),
		mcp.WithBoolean("full_page", mcp.Description("Capture the full scroll height instead of just the viewport.")),
	)
}

func (d *deps) handlePageScreenshot(_ context.Context, _ mcp.CallToolRequest, a pageScreenshotArgs) (*mcp.CallToolResult, error) {
	if a.Path == "" {
		return mcp.NewToolResultError("path is required"), nil
	}
	opts := browser.CdpScreenshotOpts{FullPage: a.FullPage}
	err := d.withConn(portOr(a.Port), func(c *browser.CDPConn) error {
		return browser.CdpScreenshot(c, a.Path, opts)
	})
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	return mcp.NewToolResultText("screenshot saved to " + a.Path), nil
}