//go:build linux || freebsd
// +build linux freebsd

package cookie

import (
	"bufio"
	"fmt"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"time"

	"codeberg.org/petrbalvin/goget/internal/core"
	"golang.org/x/net/publicsuffix"
)

// Jar wraps http.CookieJar with Netscape format import/export.
type Jar struct {
	*cookiejar.Jar
	mu      sync.Mutex
	cookies map[string][]*http.Cookie // domain -> cookies (for export)
}

// NewJar creates a new cookie jar with public suffix support.
func NewJar() (*Jar, error) {
	jar, err := cookiejar.New(&cookiejar.Options{
		PublicSuffixList: publicsuffix.List,
	})
	if err != nil {
		return nil, err
	}
	return &Jar{
		Jar:     jar,
		cookies: make(map[string][]*http.Cookie),
	}, nil
}

// SetCookies stores cookies in the jar and tracks them for export.
func (j *Jar) SetCookies(u *url.URL, cookies []*http.Cookie) {
	j.Jar.SetCookies(u, cookies)

	j.mu.Lock()
	defer j.mu.Unlock()
	for _, c := range cookies {
		// Key the export map by the cookie's effective domain, not the
		// URL hostname. A cookie set for "example.com" via a request to
		// "www.example.com" must round-trip through SaveToFile/LoadFromFile
		// keyed by "example.com", otherwise the second SetCookies call
		// (from LoadFromFile) lands under a different map key and the
		// cookies appear to be silently lost between sessions.
		key := cookieStorageKey(c, u)
		j.cookies[key] = append(j.cookies[key], c)
	}
}

// cookieStorageKey returns the canonical (no leading dot) domain used as
// the storage key for the export map. It prefers the cookie's own Domain
// attribute (which reflects the cookie's actual scope) and falls back to
// the URL hostname for host-only cookies (those without a Domain attr).
func cookieStorageKey(c *http.Cookie, u *url.URL) string {
	if c.Domain != "" {
		return strings.TrimPrefix(c.Domain, ".")
	}
	return u.Hostname()
}

// LoadFromFile loads cookies from a file in Netscape format.
func (j *Jar) LoadFromFile(path string) error {
	if path == "" {
		return nil
	}

	file, err := os.Open(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return fmt.Errorf("failed to open cookie jar: %w", err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		fields := strings.Split(line, "\t")
		if len(fields) < 7 {
			continue
		}

		domain := fields[0]
		path := fields[2]
		expiresStr := fields[4]
		name := fields[5]
		value := fields[6]

		expires, err := strconv.ParseInt(expiresStr, 10, 64)
		if err != nil {
			continue
		}

		if expires > 0 && time.Now().Unix() > expires {
			continue
		}

		// Strip the leading dot from the Netscape-format domain so the
		// round-trip back through SetCookies uses a stable key. Go's
		// net/url strips the leading dot from Hostname() since Go 1.20,
		// but matching that behaviour here makes the export map key
		// independent of Go stdlib version.
		domainBare := strings.TrimPrefix(domain, ".")

		scheme := "https"
		if fields[3] != "TRUE" {
			scheme = "http"
		}
		u := &url.URL{
			Scheme: scheme,
			Host:   domainBare,
			Path:   path,
		}

		cookie := &http.Cookie{
			Name:    name,
			Value:   value,
			Path:    path,
			Domain:  domainBare,
			Expires: time.Unix(expires, 0),
			Secure:  fields[3] == "TRUE",
		}

		j.SetCookies(u, []*http.Cookie{cookie})
	}

	return scanner.Err()
}

// SaveToFile saves cookies to a file in Netscape format.
func (j *Jar) SaveToFile(path string) error {
	if path == "" {
		return nil
	}

	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		return err
	}

	file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		return fmt.Errorf("failed to create cookie jar: %w", err)
	}
	defer file.Close()

	fmt.Fprintln(file, "# Netscape HTTP Cookie File")
	fmt.Fprintf(file, "# Generated by goget %s at %s\n", core.Version, time.Now().Format(time.RFC3339))
	fmt.Fprintln(file, "# Format: domain flag path secure expiration name value")
	fmt.Fprintln(file)

	j.mu.Lock()
	defer j.mu.Unlock()

	for domain, cookies := range j.cookies {
		for _, c := range cookies {
			secure := "FALSE"
			if c.Secure {
				secure = "TRUE"
			}
			// The map key is always stored without a leading dot, but
			// the Netscape format expects one — always emit it.
			expires := c.Expires.Unix()
			if expires <= 0 {
				expires = time.Now().Add(365 * 24 * time.Hour).Unix()
			}
			fmt.Fprintf(file, ".%s\t%s\t%s\t%s\t%d\t%s\t%s\n",
				domain,
				"TRUE",
				c.Path,
				secure,
				expires,
				c.Name,
				c.Value,
			)
		}
	}

	return nil
}

// GetCookieCount returns the number of cookies for a given URL.
func (j *Jar) GetCookieCount(u *url.URL) int {
	return len(j.Cookies(u))
}