package amazon

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"regexp"
	"strings"
	"time"

	"git.pengzhan.dev/haopengzhan/hireme/internal/crawler"
	"git.pengzhan.dev/haopengzhan/hireme/internal/logger"
)

type AmazonCrawler struct {
	client *http.Client
}

func NewAmazonCrawler() *AmazonCrawler {
	return NewAmazonCrawlerWithClient(&http.Client{
		Timeout: 30 * time.Second,
	})
}

func NewAmazonCrawlerWithClient(client *http.Client) *AmazonCrawler {
	return &AmazonCrawler{
		client: client,
	}
}

func (c *AmazonCrawler) CanHandle(platform string) bool {
	p := strings.ToLower(platform)
	return p == "amazon" || p == "aws" || strings.Contains(p, "amazon.jobs")
}

type amazonSearchResponse struct {
	Hits int             `json:"hits"`
	Jobs []amazonJobItem `json:"jobs"`
}

type amazonJobItem struct {
	ID                  string `json:"id"`
	IDIsp               string `json:"id_icims"`
	Title               string `json:"title"`
	Company             string `json:"company_name"`
	Location            string `json:"location"`
	City                string `json:"city"`
	State               string `json:"state"`
	Country             string `json:"country_code"`
	JobPath             string `json:"job_path"`
	Description         string `json:"description"`
	BasicQualifications string `json:"basic_qualifications"`
	PreferredQuals      string `json:"preferred_qualifications"`
	JobCategory         string `json:"job_category"`
	JobFamily           string `json:"job_family_name"`
	PostedDate          string `json:"posted_date"`
}

func (c *AmazonCrawler) DiscoverJobs(ctx context.Context, targetURL string) ([]crawler.DiscoveredJob, error) {
	seen := make(map[string]bool)
	var discovered []crawler.DiscoveredJob

	searchAPI := targetURL
	if !strings.Contains(searchAPI, "search.json") {
		u, err := url.Parse(targetURL)
		if err == nil && u.Host != "" {
			q := u.Query()
			searchAPI = fmt.Sprintf("https://www.amazon.jobs/en/search.json?%s", q.Encode())
		} else {
			searchAPI = fmt.Sprintf("https://www.amazon.jobs/en/search.json?base_query=%s&loc_query=Seattle%%2C+WA%%2C+USA", url.QueryEscape(targetURL))
		}
	}

	resultLimit := 100
	for page := 0; page < 5; page++ {
		offset := page * resultLimit
		reqURL := searchAPI
		if strings.Contains(reqURL, "?") {
			reqURL = fmt.Sprintf("%s&result_limit=%d&offset=%d", searchAPI, resultLimit, offset)
		} else {
			reqURL = fmt.Sprintf("%s?result_limit=%d&offset=%d", searchAPI, resultLimit, offset)
		}

		body, err := c.fetchURL(ctx, reqURL)
		if err != nil {
			if page == 0 {
				return nil, err
			}
			break
		}

		var resp amazonSearchResponse
		if err := json.Unmarshal([]byte(body), &resp); err != nil {
			if page == 0 {
				return nil, fmt.Errorf("failed to parse Amazon search response: %w", err)
			}
			break
		}

		if len(resp.Jobs) == 0 {
			break
		}

		newFound := false
		for _, job := range resp.Jobs {
			jobID := job.ID
			if jobID == "" {
				jobID = job.IDIsp
			}
			if jobID == "" {
				continue
			}

			applyURL := fmt.Sprintf("https://www.amazon.jobs/en/jobs/%s", jobID)
			if job.JobPath != "" {
				if strings.HasPrefix(job.JobPath, "http") {
					applyURL = job.JobPath
				} else {
					applyURL = "https://www.amazon.jobs" + job.JobPath
				}
			}

			if !seen[applyURL] {
				seen[applyURL] = true
				newFound = true
				discovered = append(discovered, crawler.DiscoveredJob{
					CanonicalID: fmt.Sprintf("amazon:%s", jobID),
					ApplyURL:    applyURL,
				})
			}
		}

		if !newFound || len(resp.Jobs) < resultLimit {
			break
		}
	}

	logger.Log.Infow("Amazon discovery finished", "found_count", len(discovered))
	return discovered, nil
}

func (c *AmazonCrawler) FetchJobDetail(ctx context.Context, applyURL string) (*crawler.ExtractedJob, error) {
	jobID := parseAmazonJobID(applyURL)
	if jobID == "" {
		jobID = fmt.Sprintf("%x", sha256.Sum256([]byte(applyURL)))[:16]
	}

	jsonURL := fmt.Sprintf("https://www.amazon.jobs/en/jobs/%s.json", jobID)
	body, err := c.fetchURL(ctx, jsonURL)
	if err == nil && json.Valid([]byte(body)) {
		var detail struct {
			Job amazonJobItem `json:"job"`
		}
		if err := json.Unmarshal([]byte(body), &detail); err == nil && detail.Job.Title != "" {
			j := detail.Job
			var sb strings.Builder
			if j.Description != "" {
				sb.WriteString("## Description\n\n")
				sb.WriteString(cleanHTML(j.Description))
				sb.WriteString("\n\n")
			}
			if j.BasicQualifications != "" {
				sb.WriteString("## Basic Qualifications\n\n")
				sb.WriteString(cleanHTML(j.BasicQualifications))
				sb.WriteString("\n\n")
			}
			if j.PreferredQuals != "" {
				sb.WriteString("## Preferred Qualifications\n\n")
				sb.WriteString(cleanHTML(j.PreferredQuals))
				sb.WriteString("\n\n")
			}

			company := "Amazon"
			if j.Company != "" {
				company = j.Company
			}
			loc := j.Location
			if loc == "" && j.City != "" {
				loc = fmt.Sprintf("%s, %s, %s", j.City, j.State, j.Country)
			}
			if loc == "" {
				loc = "Seattle, WA, USA"
			}

			return &crawler.ExtractedJob{
				CanonicalID: fmt.Sprintf("amazon:%s", jobID),
				Title:       j.Title,
				Company:     company,
				Location:    loc,
				ApplyURL:    applyURL,
				RawContent:  sb.String(),
			}, nil
		}
	}

	htmlBody, err := c.fetchURL(ctx, applyURL)
	if err != nil {
		return nil, err
	}

	title := extractRegex(htmlBody, `<h1[^>]*class="[^"]*title[^"]*"[^>]*>(.*?)</h1>`)
	if title == "" {
		title = extractRegex(htmlBody, `<h1[^>]*>(.*?)</h1>`)
	}
	if title == "" {
		title = "Software Engineer - Amazon"
	}

	return &crawler.ExtractedJob{
		CanonicalID: fmt.Sprintf("amazon:%s", jobID),
		Title:       cleanHTML(title),
		Company:     "Amazon",
		Location:    "Seattle, WA, USA",
		ApplyURL:    applyURL,
		RawContent:  cleanHTML(htmlBody),
	}, nil
}

func (c *AmazonCrawler) fetchURL(ctx context.Context, urlStr string) (string, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", urlStr, nil)
	if err != nil {
		return "", 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")
	req.Header.Set("Accept", "application/json, text/html, */*")

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

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("HTTP GET returned status %d for %s", resp.StatusCode, urlStr)
	}

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

	return string(body), nil
}

func parseAmazonJobID(u string) string {
	re := regexp.MustCompile(`/jobs/([0-9A-Za-z\-]+)`)
	m := re.FindStringSubmatch(u)
	if len(m) >= 2 {
		return strings.TrimSuffix(m[1], ".json")
	}
	return ""
}

func extractRegex(s, pattern string) string {
	re := regexp.MustCompile(pattern)
	m := re.FindStringSubmatch(s)
	if len(m) >= 2 {
		return m[1]
	}
	return ""
}

func cleanHTML(s string) string {
	s = strings.ReplaceAll(s, "<b>", "**")
	s = strings.ReplaceAll(s, "</b>", "**")
	s = strings.ReplaceAll(s, "<strong>", "**")
	s = strings.ReplaceAll(s, "</strong>", "**")
	s = strings.ReplaceAll(s, "<br>", "\n")
	s = strings.ReplaceAll(s, "<br/>", "\n")
	s = strings.ReplaceAll(s, "<br />", "\n")
	s = strings.ReplaceAll(s, "<li>", "- ")
	s = strings.ReplaceAll(s, "</li>", "\n")
	s = strings.ReplaceAll(s, "<ul>", "\n")
	s = strings.ReplaceAll(s, "</ul>", "\n")
	s = strings.ReplaceAll(s, "<p>", "\n")
	s = strings.ReplaceAll(s, "</p>", "\n")
	reTags := regexp.MustCompile(`<[^>]*>`)
	s = reTags.ReplaceAllString(s, "")
	return strings.TrimSpace(s)
}