package crawler

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"golang.org/x/net/html"
)

type GenericCrawler struct {
	client *http.Client
}

func NewGenericCrawler() *GenericCrawler {
	return &GenericCrawler{
		client: &http.Client{
			Timeout: 15 * time.Second,
		},
	}
}

func (c *GenericCrawler) CanHandle(platform string) bool {
	p := strings.ToLower(platform)
	return p == "generic" || p == "greenhouse" || p == "lever" || p == "linkedin"
}

func (c *GenericCrawler) DiscoverJobs(ctx context.Context, targetURL string) ([]DiscoveredJob, error) {
	cid := GenerateCanonicalID(extractCompanyFromURL(targetURL), "Generic Job", targetURL)
	return []DiscoveredJob{
		{
			CanonicalID: cid,
			ApplyURL:    targetURL,
		},
	}, nil
}

func (c *GenericCrawler) FetchJobDetail(ctx context.Context, applyURL string) (*ExtractedJob, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", applyURL, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36")

	resp, err := c.client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("HTTP request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HTTP status error %d for URL %s", resp.StatusCode, applyURL)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response body: %w", err)
	}

	rawText := ExtractTextFromHTML(string(body))
	title := ExtractTitleFromHTML(string(body))
	if title == "" {
		title = "Job Opportunity"
	}

	company := extractCompanyFromURL(applyURL)
	cid := GenerateCanonicalID(company, title, applyURL)

	return &ExtractedJob{
		CanonicalID: cid,
		Title:       title,
		Company:     company,
		Location:    "Remote / Listed Location",
		ApplyURL:    applyURL,
		RawContent:  rawText,
	}, nil
}

func ExtractTitleFromHTML(htmlContent string) string {
	doc, err := html.Parse(strings.NewReader(htmlContent))
	if err != nil {
		return ""
	}
	var title string
	var f func(*html.Node)
	f = func(n *html.Node) {
		if n.Type == html.ElementNode && n.Data == "title" && n.FirstChild != nil {
			title = strings.TrimSpace(n.FirstChild.Data)
			return
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			f(c)
		}
	}
	f(doc)
	return title
}

func ExtractTextFromHTML(htmlContent string) string {
	doc, err := html.Parse(strings.NewReader(htmlContent))
	if err != nil {
		return htmlContent
	}
	var b strings.Builder
	var f func(*html.Node)
	f = func(n *html.Node) {
		if n.Type == html.ElementNode && (n.Data == "script" || n.Data == "style") {
			return
		}
		if n.Type == html.TextNode {
			txt := strings.TrimSpace(n.Data)
			if txt != "" {
				b.WriteString(txt)
				b.WriteString(" ")
			}
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			f(c)
		}
	}
	f(doc)
	return b.String()
}

func extractCompanyFromURL(u string) string {
	if strings.Contains(u, "google") {
		return "Google"
	} else if strings.Contains(u, "linkedin") {
		return "LinkedIn Network"
	} else if strings.Contains(u, "greenhouse") {
		return "Greenhouse Client"
	} else if strings.Contains(u, "lever") {
		return "Lever Client"
	}
	return "Tech Corp"
}