package tide

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"

	"github.com/goccy/go-yaml"
)

var (
	placeholderRe = regexp.MustCompile(`\{\{([^{}]+)\}\}`)
	jwtShapeRe    = regexp.MustCompile(`eyJ[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+`)
	invShapeRe    = regexp.MustCompile(`inv_[A-Za-z0-9]{8,}`)
	cookieRe      = regexp.MustCompile(`(?i)auth_token=([^;]+)`)
	secretFormRe  = regexp.MustCompile(`(?i)client_secret=([^&\s]+)`)
	pkceFormRe    = regexp.MustCompile(`(?i)code_verifier=([^&\s]+)`)
)

// Store holds named capture values. When Path is set it is a mode-0600 private file.
type Store struct {
	mu   sync.Mutex
	path string
	vals map[string]string
}

// OpenStore loads or creates a private variable map. Empty path is memory-only.
func OpenStore(path string) (*Store, error) {
	s := &Store{path: path, vals: make(map[string]string)}
	if strings.TrimSpace(path) == "" {
		return s, nil
	}
	abs, err := filepath.Abs(path)
	if err != nil {
		return nil, fmt.Errorf("tide: vars path: %w", err)
	}
	s.path = abs
	st, err := os.Stat(abs)
	if err == nil {
		if st.IsDir() {
			return nil, fmt.Errorf("tide: vars %q is a directory", path)
		}
		raw, err := os.ReadFile(abs)
		if err != nil {
			return nil, fmt.Errorf("tide: read vars: %w", err)
		}
		if len(strings.TrimSpace(string(raw))) > 0 {
			if err := yaml.Unmarshal(raw, &s.vals); err != nil {
				return nil, fmt.Errorf("tide: parse vars: %w", err)
			}
			if s.vals == nil {
				s.vals = make(map[string]string)
			}
		}
		if err := os.Chmod(abs, 0o600); err != nil {
			return nil, fmt.Errorf("tide: chmod vars: %w", err)
		}
		return s, nil
	}
	if !os.IsNotExist(err) {
		return nil, fmt.Errorf("tide: stat vars: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(abs), 0o755); err != nil {
		return nil, fmt.Errorf("tide: create vars dir: %w", err)
	}
	if err := os.WriteFile(abs, []byte("{}\n"), 0o600); err != nil {
		return nil, fmt.Errorf("tide: create vars: %w", err)
	}
	_ = os.Chmod(abs, 0o600)
	return s, nil
}

// Save writes the map as YAML with mode 0600. Memory-only stores are a no-op.
func (s *Store) Save() error {
	if s == nil || s.path == "" {
		return nil
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	keys := make([]string, 0, len(s.vals))
	for k := range s.vals {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	var b strings.Builder
	if len(keys) == 0 {
		b.WriteString("{}\n")
	}
	for _, k := range keys {
		fmt.Fprintf(&b, "%s: %s\n", strconv.Quote(k), strconv.Quote(s.vals[k]))
	}
	raw := []byte(b.String())
	tmp, err := os.CreateTemp(filepath.Dir(s.path), ".vars-*.tmp")
	if err != nil {
		return fmt.Errorf("tide: vars temp: %w", err)
	}
	tmpName := tmp.Name()
	if _, err := tmp.Write(raw); err != nil {
		_ = tmp.Close()
		_ = os.Remove(tmpName)
		return err
	}
	_ = tmp.Chmod(0o600)
	if err := tmp.Close(); err != nil {
		_ = os.Remove(tmpName)
		return err
	}
	if err := os.Rename(tmpName, s.path); err != nil {
		_ = os.Remove(tmpName)
		return err
	}
	return os.Chmod(s.path, 0o600)
}

// Get returns a stored value.
func (s *Store) Get(name string) (string, bool) {
	if s == nil {
		return "", false
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	v, ok := s.vals[name]
	return v, ok
}

// Set stores a named value.
func (s *Store) Set(name, value string) {
	if s == nil {
		return
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	s.vals[name] = value
}

// Expand replaces {{name}} placeholders. Unresolved names fail before HTTP send.
func (s *Store) Expand(text string) (string, error) {
	if !strings.Contains(text, "{{") {
		return text, nil
	}
	if s == nil {
		m := placeholderRe.FindStringSubmatch(text)
		if len(m) > 1 {
			return "", fmt.Errorf("tide: unresolved placeholder %q", m[1])
		}
		return "", fmt.Errorf("tide: unresolved placeholder")
	}
	var missing []string
	s.mu.Lock()
	out := placeholderRe.ReplaceAllStringFunc(text, func(m string) string {
		name := m[2 : len(m)-2]
		v, ok := s.vals[name]
		if !ok {
			missing = append(missing, name)
			return m
		}
		return v
	})
	s.mu.Unlock()
	if len(missing) > 0 {
		return "", fmt.Errorf("tide: unresolved placeholder %q", missing[0])
	}
	return out, nil
}

func expandRequest(req Request, store *Store) (Request, error) {
	out := req
	var err error
	out.Path, err = store.Expand(req.Path)
	if err != nil {
		return Request{}, err
	}
	out.Query, err = store.Expand(req.Query)
	if err != nil {
		return Request{}, err
	}
	if req.Headers != nil {
		out.Headers = make(map[string]string, len(req.Headers))
		for k, v := range req.Headers {
			out.Headers[k], err = store.Expand(v)
			if err != nil {
				return Request{}, err
			}
		}
	}
	body, err := store.Expand(string(req.Body))
	if err != nil {
		return Request{}, err
	}
	out.Body = Body(body)
	return out, nil
}

func expandResponse(resp Response, store *Store) (Response, error) {
	out := resp
	var err error
	if resp.Headers != nil {
		out.Headers = make(map[string]string, len(resp.Headers))
		for k, v := range resp.Headers {
			out.Headers[k], err = store.Expand(v)
			if err != nil {
				return Response{}, err
			}
		}
	}
	body, err := store.Expand(string(resp.Body))
	if err != nil {
		return Response{}, err
	}
	out.Body = Body(body)
	return out, nil
}

// CaptureStep writes named values from the step into the store.
func CaptureStep(store *Store, step *Step) error {
	if store == nil || step == nil || len(step.Capture) == 0 {
		return nil
	}
	for _, rule := range step.Capture {
		val, err := extractCapture(rule, step.Request, step.Response)
		if err != nil {
			return fmt.Errorf("tide: capture %q: %w", rule.As, err)
		}
		if strings.TrimSpace(val) == "" {
			return fmt.Errorf("tide: capture %q was empty", rule.As)
		}
		store.Set(rule.As, val)
	}
	return nil
}

func extractCapture(rule CaptureRule, req Request, resp Response) (string, error) {
	from := strings.TrimSpace(rule.From)
	if from == "" {
		from = "response.json"
	}
	switch from {
	case "response.json":
		v, err := jsonPathValue([]byte(resp.Body), rule.Path)
		if err != nil {
			return "", err
		}
		return scalarString(v), nil
	case "response.json.query":
		v, err := jsonPathValue([]byte(resp.Body), rule.Path)
		if err != nil {
			return "", err
		}
		raw := scalarString(v)
		u, err := url.Parse(raw)
		if err != nil {
			return "", err
		}
		q := u.Query().Get(rule.Name)
		if q == "" {
			return "", fmt.Errorf("missing JSON URL query %s", rule.Name)
		}
		return q, nil
	case "response.header":
		v := headerValue(resp.Headers, rule.Name)
		if v == "" {
			return "", fmt.Errorf("missing response header %s", rule.Name)
		}
		return v, nil
	case "response.query":
		loc := headerValue(resp.Headers, "Location")
		if loc == "" {
			return "", fmt.Errorf("missing Location header")
		}
		u, err := url.Parse(loc)
		if err != nil {
			return "", err
		}
		v := u.Query().Get(rule.Name)
		if v == "" {
			return "", fmt.Errorf("missing response query %s", rule.Name)
		}
		return v, nil
	case "response.location.query":
		loc := headerValue(resp.Headers, "Location")
		if loc == "" {
			return "", fmt.Errorf("missing Location header")
		}
		u, err := url.Parse(loc)
		if err != nil {
			return "", err
		}
		v := u.Query().Get(rule.Name)
		if v == "" {
			return "", fmt.Errorf("missing Location query %s", rule.Name)
		}
		return v, nil
	case "request.form":
		v, err := formValue(string(req.Body), rule.Name)
		if err != nil {
			return "", err
		}
		if v == "" {
			return "", fmt.Errorf("missing form field %s", rule.Name)
		}
		return v, nil
	case "request.header":
		v := headerValue(req.Headers, rule.Name)
		if v == "" {
			return "", fmt.Errorf("missing request header %s", rule.Name)
		}
		return v, nil
	case "request.query":
		q, err := url.ParseQuery(req.Query)
		if err != nil {
			return "", err
		}
		v := q.Get(rule.Name)
		if v == "" {
			return "", fmt.Errorf("missing request query %s", rule.Name)
		}
		return v, nil
	default:
		return "", fmt.Errorf("unknown capture from %q", from)
	}
}

func formValue(body, name string) (string, error) {
	vals, err := url.ParseQuery(body)
	if err != nil {
		return "", err
	}
	return vals.Get(name), nil
}

func jsonPathValue(raw []byte, path string) (any, error) {
	if strings.TrimSpace(path) == "" {
		return nil, fmt.Errorf("json path is required")
	}
	root, err := decodeJSON(raw)
	if err != nil {
		return nil, err
	}
	v, err := walkJSONPath(root, path)
	if err != nil {
		return nil, err
	}
	return v, nil
}

func walkJSONPath(root any, path string) (any, error) {
	path = strings.TrimSpace(path)
	if path == "$" || path == "" {
		return root, nil
	}
	if !strings.HasPrefix(path, "$") {
		path = "$." + path
	}
	cur := root
	rest := strings.TrimPrefix(path, "$")
	for rest != "" {
		switch {
		case strings.HasPrefix(rest, "."):
			rest = rest[1:]
			name, next := splitPathSeg(rest)
			if name == "" {
				return nil, fmt.Errorf("invalid json path %s", path)
			}
			obj, ok := cur.(map[string]any)
			if !ok {
				return nil, fmt.Errorf("%s is not an object", path)
			}
			v, ok := obj[name]
			if !ok {
				return nil, fmt.Errorf("missing %s", "$."+name)
			}
			cur = v
			rest = next
		case strings.HasPrefix(rest, "["):
			end := strings.IndexByte(rest, ']')
			if end < 0 {
				return nil, fmt.Errorf("invalid json path %s", path)
			}
			idx, err := atoi(rest[1:end])
			if err != nil {
				return nil, err
			}
			arr, ok := cur.([]any)
			if !ok || idx < 0 || idx >= len(arr) {
				return nil, fmt.Errorf("missing %s[%d]", path, idx)
			}
			cur = arr[idx]
			rest = rest[end+1:]
		default:
			return nil, fmt.Errorf("invalid json path %s", path)
		}
	}
	return cur, nil
}

func splitPathSeg(s string) (name, rest string) {
	i := 0
	for i < len(s) && s[i] != '.' && s[i] != '[' {
		i++
	}
	return s[:i], s[i:]
}

func atoi(s string) (int, error) {
	n := 0
	if s == "" {
		return 0, fmt.Errorf("empty index")
	}
	for _, c := range s {
		if c < '0' || c > '9' {
			return 0, fmt.Errorf("invalid index %q", s)
		}
		n = n*10 + int(c-'0')
	}
	return n, nil
}

func scalarString(v any) string {
	switch t := v.(type) {
	case nil:
		return ""
	case string:
		return t
	case json.Number:
		return string(t)
	case bool:
		return fmt.Sprintf("%v", t)
	default:
		return fmt.Sprintf("%v", t)
	}
}

// ScrubStep replaces stored capture values with {{name}} in kept fields.
func ScrubStep(store *Store, step *Step) error {
	if store == nil || step == nil {
		return nil
	}
	pairs := store.replacements()
	step.Request.Path = replaceAll(step.Request.Path, pairs)
	step.Request.Query = replaceAll(step.Request.Query, pairs)
	step.Request.Headers = scrubMap(step.Request.Headers, pairs)
	step.Request.Body = Body(replaceAll(string(step.Request.Body), pairs))
	step.Response.Headers = scrubMap(step.Response.Headers, pairs)
	step.Response.Body = Body(replaceAll(string(step.Response.Body), pairs))
	return rejectUnclassifiedCredentials(*step)
}

func (s *Store) replacements() [][2]string {
	if s == nil {
		return nil
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	keys := make([]string, 0, len(s.vals))
	for k, v := range s.vals {
		if v != "" {
			keys = append(keys, k)
		}
	}
	sort.Slice(keys, func(i, j int) bool {
		return len(s.vals[keys[i]]) > len(s.vals[keys[j]])
	})
	out := make([][2]string, 0, len(keys))
	for _, k := range keys {
		out = append(out, [2]string{s.vals[k], "{{" + k + "}}"})
	}
	return out
}

func scrubMap(in map[string]string, pairs [][2]string) map[string]string {
	if in == nil {
		return nil
	}
	out := make(map[string]string, len(in))
	for k, v := range in {
		out[k] = replaceAll(v, pairs)
	}
	return out
}

func replaceAll(s string, pairs [][2]string) string {
	for _, p := range pairs {
		if p[0] == "" {
			continue
		}
		olds := []string{p[0]}
		if esc := phpJSONEscape(p[0]); esc != p[0] {
			olds = append(olds, esc)
		}
		for _, old := range olds {
			if len(old) >= 8 {
				s = strings.ReplaceAll(s, old, p[1])
				continue
			}
			s = replaceIsolated(s, old, p[1])
		}
	}
	return s
}

func phpJSONEscape(s string) string {
	return strings.ReplaceAll(s, "/", `\/`)
}

func replaceIsolated(s, old, neu string) string {
	if old == "" || s == "" {
		return s
	}
	var b strings.Builder
	i := 0
	for i < len(s) {
		j := strings.Index(s[i:], old)
		if j < 0 {
			b.WriteString(s[i:])
			break
		}
		j += i
		leftOK := j == 0 || !isIdentByte(s[j-1])
		right := j + len(old)
		rightOK := right == len(s) || !isIdentByte(s[right])
		if leftOK && rightOK {
			b.WriteString(s[i:j])
			b.WriteString(neu)
			i = right
			continue
		}
		b.WriteString(s[i : j+len(old)])
		i = j + len(old)
	}
	return b.String()
}

func isIdentByte(c byte) bool {
	return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_'
}

func rejectUnclassifiedCredentials(step Step) error {
	check := func(label, s string) error {
		if hit := remainingCredential(s); hit != "" {
			return fmt.Errorf("unclassified credential-shaped value (%s) in %s step %s", hit, label, step.ID)
		}
		return nil
	}
	for k, v := range step.Request.Headers {
		if err := check("request header "+k, v); err != nil {
			return err
		}
	}
	if err := check("request query", step.Request.Query); err != nil {
		return err
	}
	if err := check("request body", string(step.Request.Body)); err != nil {
		return err
	}
	for k, v := range step.Response.Headers {
		if err := check("response header "+k, v); err != nil {
			return err
		}
	}
	return check("response body", string(step.Response.Body))
}

func remainingCredential(s string) string {
	s = placeholderRe.ReplaceAllString(s, "")
	if s == "" {
		return ""
	}
	if jwtShapeRe.MatchString(s) {
		return "jwt"
	}
	if invShapeRe.MatchString(s) {
		return "token"
	}
	if cookieRe.MatchString(s) {
		return "cookie"
	}
	if secretFormRe.MatchString(s) {
		return "oauth_secret"
	}
	if pkceFormRe.MatchString(s) {
		return "pkce"
	}
	return ""
}

func varsOutsideFixtures(varsPath, fixtures string) error {
	if varsPath == "" || fixtures == "" {
		return nil
	}
	absVars, err := filepath.Abs(varsPath)
	if err != nil {
		return fmt.Errorf("tide: vars path: %w", err)
	}
	absFix, err := filepath.Abs(fixtures)
	if err != nil {
		return fmt.Errorf("tide: fixtures path: %w", err)
	}
	if absVars == absFix || strings.HasPrefix(absVars, absFix+string(os.PathSeparator)) {
		return fmt.Errorf("tide: vars file %q must be outside fixtures %q", varsPath, fixtures)
	}
	return nil
}

func mergeRouteCaptures(step *Step, rules Rules) {
	if step == nil || len(step.Capture) > 0 {
		return
	}
	route := rules.Match(step.Request.Method, step.Request.Path)
	if route != nil && len(route.Capture) > 0 {
		step.Capture = append([]CaptureRule(nil), route.Capture...)
	}
}

func recordedResponseHeaders(h http.Header, rules Rules, method, path string) map[string]string {
	route := rules.Match(method, path)
	if keep := rules.responseHeaders(route); len(keep) > 0 {
		return filterHeaders(h, keep)
	}
	return keepResponseHeaders(h)
}