package api

import (
	"fmt"
	"net/url"
	"strings"
)

// PageRef holds parsed Confluence page reference from a URL.
type PageRef struct {
	BaseURL  string // e.g., "https://confluence.example.com"
	PageID   string // numeric ID if available
	SpaceKey string // from /display/SPACE/... format
	Title    string // URL-decoded page title
}

// ParsePageURL parses a Confluence Server/Data Center page URL into a PageRef.
//
// Supported formats:
//   - https://confluence.example.com/pages/viewpage.action?pageId=12345
//   - https://confluence.example.com/display/SPACE/Page+Title
//   - https://confluence.example.com/display/SPACE/Page+Title/Sub+Page
func ParsePageURL(rawURL string) (*PageRef, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, fmt.Errorf("parsing URL: %w", err)
	}

	if u.Scheme == "" || u.Host == "" {
		return nil, fmt.Errorf("URL must include scheme and host: %s", rawURL)
	}

	baseURL := u.Scheme + "://" + u.Host
	if u.Port() != "" && !strings.Contains(u.Host, ":") {
		baseURL = u.Scheme + "://" + u.Host + ":" + u.Port()
	}

	path := strings.TrimRight(u.Path, "/")

	// Format 1: /pages/viewpage.action?pageId=12345
	if strings.HasSuffix(path, "/pages/viewpage.action") || path == "/pages/viewpage.action" {
		pageID := u.Query().Get("pageId")
		if pageID == "" {
			return nil, fmt.Errorf("URL has viewpage.action but no pageId parameter: %s", rawURL)
		}
		return &PageRef{
			BaseURL: baseURL,
			PageID:  pageID,
		}, nil
	}

	// Format 2: /display/SPACE/Page+Title
	if idx := strings.Index(path, "/display/"); idx != -1 {
		rest := path[idx+len("/display/"):]
		parts := strings.SplitN(rest, "/", 2)
		if len(parts) < 2 || parts[0] == "" || parts[1] == "" {
			return nil, fmt.Errorf("URL display format requires /display/SPACE/Title: %s", rawURL)
		}
		spaceKey := parts[0]
		// The title may contain slashes for sub-pages; take the last segment
		titleEncoded := parts[1]
		// Confluence uses + for spaces in URL paths
		title := strings.ReplaceAll(titleEncoded, "+", " ")
		title, err = url.PathUnescape(title)
		if err != nil {
			return nil, fmt.Errorf("decoding page title: %w", err)
		}
		return &PageRef{
			BaseURL:  baseURL,
			SpaceKey: spaceKey,
			Title:    title,
		}, nil
	}

	return nil, fmt.Errorf("unrecognized Confluence URL format: %s", rawURL)
}