package objectstorage

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

	"github.com/geo-platform/tenant-api/internal/shared/config"
)

func buildPublicURL(cfg config.ObjectStorageConfig, objectKey string, bucketInHost bool) (string, error) {
	objectKey = strings.TrimSpace(objectKey)
	if objectKey == "" {
		return "", fmt.Errorf("object key is required")
	}

	defaultScheme := "http"
	if cfg.UseSSL {
		defaultScheme = "https"
	}

	if publicBaseURL := strings.TrimSpace(cfg.PublicBaseURL); publicBaseURL != "" {
		baseURL, err := parseURLWithScheme(publicBaseURL, defaultScheme)
		if err != nil {
			return "", fmt.Errorf("parse public_base_url: %w", err)
		}
		baseURL.Path = joinEscapedPath(baseURL.Path, objectKey)
		baseURL.RawPath = ""
		return baseURL.String(), nil
	}

	endpoint := strings.TrimSpace(cfg.Endpoint)
	bucket := strings.TrimSpace(cfg.Bucket)
	if endpoint == "" || bucket == "" {
		return "", fmt.Errorf("%w: object storage endpoint or bucket is missing", ErrNotConfigured)
	}

	endpointURL, err := parseURLWithScheme(endpoint, defaultScheme)
	if err != nil {
		return "", fmt.Errorf("parse object storage endpoint: %w", err)
	}

	if bucketInHost {
		hostname := endpointURL.Hostname()
		if hostname == "" {
			return "", fmt.Errorf("invalid object storage endpoint host")
		}

		host := hostname
		if !strings.HasPrefix(host, bucket+".") {
			host = bucket + "." + host
		}
		if port := endpointURL.Port(); port != "" {
			host += ":" + port
		}

		endpointURL.Host = host
		endpointURL.Path = joinEscapedPath("", objectKey)
		endpointURL.RawPath = ""
		return endpointURL.String(), nil
	}

	endpointURL.Path = joinEscapedPath(endpointURL.Path, bucket, objectKey)
	endpointURL.RawPath = ""
	return endpointURL.String(), nil
}

func parseURLWithScheme(raw string, defaultScheme string) (*url.URL, error) {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return nil, fmt.Errorf("url is empty")
	}

	if !strings.Contains(raw, "://") {
		raw = defaultScheme + "://" + raw
	}

	parsed, err := url.Parse(raw)
	if err != nil {
		return nil, err
	}
	if parsed.Host == "" {
		return nil, fmt.Errorf("url host is empty")
	}
	return parsed, nil
}

func joinEscapedPath(basePath string, extra ...string) string {
	segments := make([]string, 0)

	appendPath := func(value string) {
		value = strings.TrimSpace(value)
		value = strings.Trim(value, "/")
		if value == "" {
			return
		}

		for _, segment := range strings.Split(value, "/") {
			segment = strings.TrimSpace(segment)
			if segment == "" {
				continue
			}
			segments = append(segments, url.PathEscape(segment))
		}
	}

	appendPath(basePath)
	for _, value := range extra {
		appendPath(value)
	}

	if len(segments) == 0 {
		return "/"
	}
	return "/" + strings.Join(segments, "/")
}