package tide

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
)

var carbonOffsetRe = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\+00:00$`)

const (
	maskDatetime = "<datetime>"
	maskID       = "<id>"
)

// DefaultUploadPrefix is the WinterCMS public uploads URL prefix
// (cms.storage.uploads.path plus /public) that url and thumb_url values are
// checked against when ReplayConfig.UploadPrefix is empty.
const DefaultUploadPrefix = "/storage/app/uploads/public"

// maskOptions configures the response-body normalizer.
type maskOptions struct {
	uploadPrefix string
}

func (o maskOptions) prefix() string {
	p := strings.TrimRight(o.uploadPrefix, "/")
	if p == "" {
		return DefaultUploadPrefix
	}
	return p
}

func normalizeJSON(raw []byte, step Step, opts maskOptions) ([]byte, []Diff) {
	if len(strings.TrimSpace(string(raw))) == 0 {
		return raw, nil
	}
	val, err := decodeJSON(raw)
	if err != nil {
		return raw, nil
	}
	var diffs []Diff
	masked := maskValue("$", val, step, opts, &diffs)
	out, err := json.Marshal(masked)
	if err != nil {
		return raw, diffs
	}
	return out, diffs
}

func maskValue(path string, val any, step Step, opts maskOptions, diffs *[]Diff) any {
	switch v := val.(type) {
	case map[string]any:
		out := make(map[string]any, len(v))
		for k, child := range v {
			out[k] = maskValue(pathJoin(path, k), child, step, opts, diffs)
		}
		return out
	case []any:
		out := make([]any, len(v))
		for i, child := range v {
			out[i] = maskValue(fmt.Sprintf("%s[%d]", path, i), child, step, opts, diffs)
		}
		return out
	default:
		return maskLeaf(path, val, step, opts, diffs)
	}
}

func maskLeaf(path string, val any, step Step, opts maskOptions, diffs *[]Diff) any {
	key := lastPathKey(path)
	if key == "slug" || disabledPath(step, path, key) {
		return val
	}
	if key == "url" || key == "thumb_url" {
		if s, ok := val.(string); ok {
			return maskUploadURL(path, s, opts.prefix(), diffs)
		}
		return val
	}
	if key == "collection_key" || key == "client_id" {
		if val == nil {
			return nil
		}
		if _, ok := val.(string); !ok {
			*diffs = append(*diffs, Diff{Path: path, Expected: "string " + key, Actual: formatValue(val)})
			return val
		}
		return maskID
	}
	if strings.HasSuffix(key, "_issued_at") {
		return maskIDValue(path, val, diffs)
	}
	if isDateKey(key) {
		return maskDate(path, val, diffs)
	}
	if isIDKey(key) {
		return maskIDValue(path, val, diffs)
	}
	return val
}

func maskDate(path string, val any, diffs *[]Diff) any {
	if val == nil {
		return nil
	}
	s, ok := val.(string)
	if !ok {
		*diffs = append(*diffs, Diff{Path: path, Expected: "Carbon +00:00 string or null", Actual: formatValue(val)})
		return val
	}
	if !carbonOffsetRe.MatchString(s) {
		*diffs = append(*diffs, Diff{Path: path, Expected: "Carbon +00:00", Actual: strconvQuote(s)})
		return val
	}
	return maskDatetime
}

func maskIDValue(path string, val any, diffs *[]Diff) any {
	if val == nil {
		return nil
	}
	n, ok := val.(json.Number)
	if !ok {
		*diffs = append(*diffs, Diff{Path: path, Expected: "integer id", Actual: formatValue(val)})
		return val
	}
	if strings.Contains(string(n), ".") {
		*diffs = append(*diffs, Diff{Path: path, Expected: "integer id", Actual: "number " + string(n)})
		return val
	}
	return maskID
}

func isDateKey(key string) bool {
	return strings.HasSuffix(key, "_at") || key == "checkpoint"
}

func isIDKey(key string) bool {
	if key == "id" {
		return true
	}
	if strings.HasSuffix(key, "_at") {
		return false
	}
	// "_ids" covers plural raw-integer-array fields such as collection_ids:
	// each array element still reaches maskLeaf individually (maskValue
	// recurses into []any before calling maskLeaf), so this masks every
	// element the same way a singular "_id" scalar would be masked.
	return strings.HasSuffix(key, "_id") || strings.HasSuffix(key, "_ids")
}

func lastPathKey(path string) string {
	path = strings.TrimPrefix(path, "$.")
	if i := strings.LastIndex(path, "."); i >= 0 {
		path = path[i+1:]
	}
	if i := strings.IndexByte(path, '['); i >= 0 {
		path = path[:i]
	}
	return path
}

func disabledPath(step Step, jsonPath, key string) bool {
	for _, rule := range step.Normalize {
		if !rule.Disable {
			continue
		}
		p := strings.TrimSpace(rule.Path)
		if p == jsonPath || p == key || strings.TrimPrefix(p, "$.") == strings.TrimPrefix(jsonPath, "$.") {
			return true
		}
	}
	return false
}

func strconvQuote(s string) string {
	return `"` + s + `"`
}

var (
	// uploadOriginalRe is <partition>/<disk_name>: Winter's partition
	// directory (the first nine characters of the disk name in three groups)
	// and a hex disk name with its extension.
	uploadOriginalRe = regexp.MustCompile(`^/([0-9a-f]{3})/([0-9a-f]{3})/([0-9a-f]{3})/([0-9a-f]{9,})(\.[a-z0-9]+)?$`)
	// uploadThumbRe is <partition>/thumb_<id>_<w>_<h>_<ox>_<oy>_<mode>.<ext>
	// (Winter getThumbFilename).
	uploadThumbRe = regexp.MustCompile(`^/([0-9a-f]{3})/([0-9a-f]{3})/([0-9a-f]{3})/thumb_([0-9]+)_([0-9]+_[0-9]+_-?[0-9]+_-?[0-9]+_[a-z0-9]+\.[a-z0-9]+)$`)
	// uploadShapeRe recognises an upload URL under any prefix.
	uploadShapeRe = regexp.MustCompile(`/[0-9a-f]{3}/[0-9a-f]{3}/[0-9a-f]{3}/(?:thumb_[0-9]+_[0-9]+_[0-9]+_-?[0-9]+_-?[0-9]+_[a-z0-9]+\.[a-z0-9]+|[0-9a-f]{9,}(?:\.[a-z0-9]+)?)$`)
)

// maskUploadURL masks the random parts of an uploaded file's URL, the
// partition and disk name of an original and the partition and file id of a
// thumbnail, after checking the shape. The prefix, thumbnail size, offsets,
// mode and extension stay visible, so a different size or extension still
// shows as a mismatch. A URL under another prefix that looks like an upload
// is a Diff; any other value is left as it is.
func maskUploadURL(path, s, prefix string, diffs *[]Diff) any {
	if rest, ok := strings.CutPrefix(s, prefix); ok && strings.HasPrefix(rest, "/") {
		if m := uploadOriginalRe.FindStringSubmatch(rest); m != nil {
			if m[1]+m[2]+m[3] != m[4][:9] {
				*diffs = append(*diffs, Diff{Path: path, Expected: "partition from the disk name", Actual: strconvQuote(s)})
				return s
			}
			return prefix + "/<partition>/<disk_name>" + m[5]
		}
		if m := uploadThumbRe.FindStringSubmatch(rest); m != nil {
			return prefix + "/<partition>/thumb_<id>_" + m[5]
		}
		*diffs = append(*diffs, Diff{Path: path, Expected: "upload URL " + prefix + "/xxx/yyy/zzz/<disk_name>", Actual: strconvQuote(s)})
		return s
	}
	if uploadShapeRe.MatchString(s) && !strings.Contains(s, "://") {
		*diffs = append(*diffs, Diff{Path: path, Expected: "upload URL under " + prefix, Actual: strconvQuote(s)})
	}
	return s
}