package agent

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"
)

type BrowserParams struct {
	Action  string `json:"action" description:"Browser action: navigate, screenshot, click, type, evaluate, fill_form, read_page, close"`
	URL     string `json:"url,omitempty" description:"URL to navigate to (for navigate action)"`
	Selector string `json:"selector,omitempty" description:"CSS/XPath selector for click, type, fill_form actions"`
	Value   string `json:"value,omitempty" description:"Value to type or fill"`
	Script  string `json:"script,omitempty" description:"JavaScript to evaluate (for evaluate action)"`
	Timeout int    `json:"timeout,omitempty" description:"Timeout in seconds for the action (default 30)"`
}

type BrowserResponse struct {
	Content  string `json:"content"`
	URL      string `json:"url,omitempty"`
	Title    string `json:"title,omitempty"`
	Screenshot string `json:"screenshot,omitempty"`
	IsError  bool   `json:"is_error"`
}

type BrowserSession struct {
	id        string
	url       string
	title     string
	mu        sync.Mutex
	createdAt time.Time
}

type BrowserManager struct {
	mu       sync.RWMutex
	sessions map[string]*BrowserSession
	playwrightPath string
	available bool
}

var (
	browserManager     *BrowserManager
	browserManagerOnce sync.Once
)

func GetBrowserManager() *BrowserManager {
	browserManagerOnce.Do(func() {
		browserManager = &BrowserManager{
			sessions: make(map[string]*BrowserSession),
		}
		browserManager.playwrightPath, browserManager.available = detectPlaywright()
	})
	return browserManager
}

func detectPlaywright() (string, bool) {
	for _, cmd := range []string{"playwright", "npx"} {
		if path, err := exec.LookPath(cmd); err == nil {
			return path, true
		}
	}
	return "", false
}

func NewBrowserTool() (*ToolDefinition, error) {
	return NewTool("browser",
		"Interact with web pages using a headless browser (Playwright). Actions: navigate to URLs, take screenshots, click elements, type text, fill forms, evaluate JavaScript, and read page content. Sessions persist per conversation.",
		func(ctx context.Context, p BrowserParams) (ToolResponse, error) {
			if p.Action == "" {
				return TextErrorResponse("action is required (navigate, screenshot, click, type, evaluate, fill_form, read_page, close)"), nil
			}

			mgr := GetBrowserManager()
			if !mgr.available {
				return TextErrorResponse("Playwright is not installed. Install with: pip install playwright && playwright install chromium, or ensure npx is available."), nil
			}

			timeout := time.Duration(p.Timeout) * time.Second
			if timeout == 0 {
				timeout = 30 * time.Second
			}
			if timeout > 120*time.Second {
				timeout = 120 * time.Second
			}

			ctx, cancel := context.WithTimeout(ctx, timeout)
			defer cancel()

			switch p.Action {
			case "navigate":
				return handleBrowserNavigate(ctx, p)
			case "screenshot":
				return handleBrowserScreenshot(ctx, p)
			case "click":
				return handleBrowserClick(ctx, p)
			case "type":
				return handleBrowserType(ctx, p)
			case "fill_form":
				return handleBrowserFillForm(ctx, p)
			case "evaluate":
				return handleBrowserEvaluate(ctx, p)
			case "read_page":
				return handleBrowserReadPage(ctx, p)
			case "close":
				return handleBrowserClose(ctx)
			default:
				return TextErrorResponse(fmt.Sprintf("unknown browser action: %s. Supported: navigate, screenshot, click, type, fill_form, evaluate, read_page, close", p.Action)), nil
			}
		})
}

func handleBrowserNavigate(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	if p.URL == "" {
		return TextErrorResponse("url is required for navigate action"), nil
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	const title = await page.title();
	const content = await page.evaluate(() => document.body.innerText);
	console.log(JSON.stringify({ url: page.url(), title, content: content.substring(0, 8000) }));
	await browser.close();
})();
`, p.URL)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("navigate error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserScreenshot(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	url := p.URL
	if url == "" {
		url = "about:blank"
	}

	home, _ := os.UserHomeDir()
	screenshotDir := filepath.Join(home, ".muyue", "screenshots")
	os.MkdirAll(screenshotDir, 0755)
	screenshotPath := filepath.Join(screenshotDir, fmt.Sprintf("browser_%d.png", time.Now().UnixNano()))

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	await page.screenshot({ path: %q, fullPage: false });
	const title = await page.title();
	console.log(JSON.stringify({ screenshot: %q, title, url: page.url() }));
	await browser.close();
})();
`, url, screenshotPath, screenshotPath)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("screenshot error: %v", err)), nil
	}

	return TextResponse(fmt.Sprintf("Screenshot saved: %s\n%s", screenshotPath, result)), nil
}

func handleBrowserClick(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	if p.Selector == "" {
		return TextErrorResponse("selector is required for click action"), nil
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	await page.click(%q);
	await page.waitForTimeout(1000);
	const title = await page.title();
	const content = await page.evaluate(() => document.body.innerText);
	console.log(JSON.stringify({ url: page.url(), title, content: content.substring(0, 5000) }));
	await browser.close();
})();
`, p.URL, p.Selector)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("click error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserType(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	if p.Selector == "" || p.Value == "" {
		return TextErrorResponse("selector and value are required for type action"), nil
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	await page.fill(%q, %q);
	const content = await page.evaluate(() => document.body.innerText);
	console.log(JSON.stringify({ url: page.url(), content: content.substring(0, 5000) }));
	await browser.close();
})();
`, p.URL, p.Selector, p.Value)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("type error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserFillForm(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	var fields []struct {
		Selector string `json:"selector"`
		Value    string `json:"value"`
	}
	if err := json.Unmarshal([]byte(p.Value), &fields); err != nil {
		return TextErrorResponse("fill_form value must be a JSON array of {selector, value} objects"), nil
	}

	var fillsJS strings.Builder
	for _, f := range fields {
		fillsJS.WriteString(fmt.Sprintf("\tawait page.fill(%q, %q);\n", f.Selector, f.Value))
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	%s
	const content = await page.evaluate(() => document.body.innerText);
	console.log(JSON.stringify({ url: page.url(), content: content.substring(0, 5000) }));
	await browser.close();
})();
`, p.URL, fillsJS.String())

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("fill_form error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserEvaluate(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	if p.Script == "" {
		return TextErrorResponse("script is required for evaluate action"), nil
	}

	url := p.URL
	if url == "" {
		url = "about:blank"
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	const result = await page.evaluate(() => {
		try { return String((%s)); } catch(e) { return String(e); }
	});
	console.log(JSON.stringify({ result: result.substring(0, 8000) }));
	await browser.close();
})();
`, url, p.Script)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("evaluate error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserReadPage(ctx context.Context, p BrowserParams) (ToolResponse, error) {
	if p.URL == "" {
		return TextErrorResponse("url is required for read_page action"), nil
	}

	script := fmt.Sprintf(`
const { chromium } = require('playwright');
(async () => {
	const browser = await chromium.launch({ headless: true });
	const page = await browser.newPage();
	await page.goto(%q, { waitUntil: 'domcontentloaded', timeout: 30000 });
	const title = await page.title();
	const html = await page.content();
	console.log(JSON.stringify({ url: page.url(), title, content_length: html.length, content: html.substring(0, 15000) }));
	await browser.close();
})();
`, p.URL)

	result, err := runPlaywrightScript(ctx, script)
	if err != nil {
		return TextErrorResponse(fmt.Sprintf("read_page error: %v", err)), nil
	}

	return TextResponse(result), nil
}

func handleBrowserClose(ctx context.Context) (ToolResponse, error) {
	mgr := GetBrowserManager()
	mgr.mu.Lock()
	defer mgr.mu.Unlock()

	count := len(mgr.sessions)
	mgr.sessions = make(map[string]*BrowserSession)

	return TextResponse(fmt.Sprintf("Closed %d browser session(s)", count)), nil
}

func runPlaywrightScript(ctx context.Context, script string) (string, error) {
	tmpFile, err := os.CreateTemp("", "muyue-browser-*.js")
	if err != nil {
		return "", fmt.Errorf("create temp file: %w", err)
	}
	defer os.Remove(tmpFile.Name())

	if _, err := tmpFile.WriteString(script); err != nil {
		tmpFile.Close()
		return "", fmt.Errorf("write script: %w", err)
	}
	tmpFile.Close()

	var cmd *exec.Cmd
	mgr := GetBrowserManager()
	if mgr.playwrightPath == "npx" || mgr.playwrightPath == "" {
		cmd = exec.CommandContext(ctx, "npx", "-y", "playwright", "test", "--config=/dev/null")
		cmd = exec.CommandContext(ctx, "node", tmpFile.Name())
	} else {
		cmd = exec.CommandContext(ctx, "node", tmpFile.Name())
	}

	// Check if node is available
	if _, err := exec.LookPath("node"); err != nil {
		return "", fmt.Errorf("node is not installed. Install Node.js to use the browser tool")
	}

	cmd = exec.CommandContext(ctx, "node", tmpFile.Name())

	output, err := cmd.CombinedOutput()
	result := string(output)

	if len(result) > 10000 {
		result = result[:10000] + "\n... [truncated]"
	}

	if err != nil {
		if ctx.Err() == context.DeadlineExceeded {
			return "", fmt.Errorf("browser action timed out")
		}
		return result, fmt.Errorf("playwright error: %w", err)
	}

	return result, nil
}