// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

// JSON functions — Harbour compatible API + Go-native extensions.
//
// Harbour compatible:
//   hb_jsonEncode(xValue [, lHumanReadable]) → cJSON
//   hb_jsonDecode(cJSON) → xValue
//
// Five extensions (Go-native, beyond Harbour):
//   JsonPretty(xValue [, cIndent]) → cPrettyJSON
//   JsonTo(xValue, cFile) → lSuccess
//   JsonFrom(cFile) → xValue
//   JsonPath(xValue, cPath) → xResult       — $.key.sub[0]
//   JsonMerge(hDest, hSrc) → hMerged        — deep merge
//   JsonType(cJSON) → cType
//   JsonValid(cJSON) → lValid
//   JsonHttpGet(cURL [, nTimeout]) → hResult — HTTP GET + JSON
//   JsonHttpPost(cURL, xBody [, nTimeout])   — HTTP POST + JSON

package hbrtl

import (
	"encoding/json"
	"five/hbrt"
	"io"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"
)

// === Harbour Compatible ===

// HB_JSONENCODE(xValue [, lHumanReadable]) → cJSON
func HbJsonEncode(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	v := t.Local(1)
	pretty := false
	if nParams >= 2 && !t.Local(2).IsNil() {
		pretty = t.Local(2).AsBool()
	}
	goVal := valueToGo(v)
	var data []byte
	var err error
	if pretty {
		data, err = json.MarshalIndent(goVal, "", "  ")
	} else {
		data, err = json.Marshal(goVal)
	}
	if err != nil {
		t.RetString("")
		return
	}
	t.RetString(string(data))
}

// HB_JSONDECODE(cJSON [, @xOut]) → xValue | nBytesParsed
//
// Two Harbour-spec calling forms:
//
//   - 1 arg : returns the decoded value (or NIL on parse error).
//   - 2 args: writes the decoded value into the byref @xOut and
//     returns the number of bytes parsed (0 on error). This is the
//     form mod_harbour / fivenode PRG code uses for ctx_get and the
//     like. Five previously implemented only the 1-arg form, so any
//     PRG that relied on the byref output saw NIL and silently fell
//     through to a default.
func HbJsonDecode(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	s := t.Local(1).AsString()
	var raw interface{}
	if err := json.Unmarshal([]byte(s), &raw); err != nil {
		if nParams >= 2 {
			t.SetLocal(2, hbrt.MakeNil())
			t.RetInt(0)
		} else {
			t.RetNil()
		}
		return
	}
	v := goToValue(raw)
	if nParams >= 2 {
		t.SetLocal(2, v)
		t.RetInt(int64(len(s)))
		return
	}
	t.RetVal(v)
}

// === Five Extensions ===

// JSONPRETTY(xValue [, cIndent]) → cPrettyJSON
func JsonPretty(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	indent := "  "
	if nParams >= 2 && !t.Local(2).IsNil() {
		indent = t.Local(2).AsString()
	}
	data, _ := json.MarshalIndent(valueToGo(t.Local(1)), "", indent)
	t.RetString(string(data))
}

// JSONTO(xValue, cFile) → lSuccess
func JsonTo(t *hbrt.Thread) {
	t.Frame(2, 0)
	defer t.EndProc()
	data, err := json.MarshalIndent(valueToGo(t.Local(1)), "", "  ")
	if err != nil {
		t.RetBool(false)
		return
	}
	t.RetBool(os.WriteFile(t.Local(2).AsString(), data, 0644) == nil)
}

// JSONFROM(cFile) → xValue
func JsonFrom(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	data, err := os.ReadFile(t.Local(1).AsString())
	if err != nil {
		t.RetNil()
		return
	}
	var raw interface{}
	if json.Unmarshal(data, &raw) != nil {
		t.RetNil()
		return
	}
	t.RetVal(goToValue(raw))
}

// JSONPATH(xValue, cPath) → xResult — $.key.sub[0]
func JsonPath(t *hbrt.Thread) {
	t.Frame(2, 0)
	defer t.EndProc()
	root := t.Local(1)
	path := strings.TrimPrefix(strings.TrimPrefix(t.Local(2).AsString(), "$."), "$")
	if path == "" {
		t.RetVal(root)
		return
	}
	t.RetVal(navigatePath(root, path))
}

func navigatePath(v hbrt.Value, path string) hbrt.Value {
	for _, part := range splitPath(path) {
		if v.IsNil() {
			return hbrt.MakeNil()
		}
		if strings.HasPrefix(part, "[") && strings.HasSuffix(part, "]") {
			idx, _ := strconv.Atoi(part[1 : len(part)-1])
			if v.IsArray() {
				arr := v.AsArray()
				if idx >= 0 && idx < len(arr.Items) {
					v = arr.Items[idx]
					continue
				}
			}
			return hbrt.MakeNil()
		}
		if v.IsHash() {
			h := v.AsHash()
			if i := h.Lookup(hbrt.MakeString(part)); i >= 0 {
				v = h.Values[i]
			} else {
				return hbrt.MakeNil()
			}
		} else {
			return hbrt.MakeNil()
		}
	}
	return v
}

func splitPath(path string) []string {
	var parts []string
	cur := ""
	for i := 0; i < len(path); i++ {
		if path[i] == '.' {
			if cur != "" {
				parts = append(parts, cur)
				cur = ""
			}
		} else if path[i] == '[' {
			if cur != "" {
				parts = append(parts, cur)
				cur = ""
			}
			j := i
			for j < len(path) && path[j] != ']' {
				j++
			}
			parts = append(parts, path[i:j+1])
			i = j
		} else {
			cur += string(path[i])
		}
	}
	if cur != "" {
		parts = append(parts, cur)
	}
	return parts
}

// JSONMERGE(hDest, hSrc) → hMerged
func JsonMerge(t *hbrt.Thread) {
	t.Frame(2, 0)
	defer t.EndProc()
	dest, src := t.Local(1), t.Local(2)
	if !dest.IsHash() || !src.IsHash() {
		t.RetVal(src)
		return
	}
	dh, sh := dest.AsHash(), src.AsHash()
	result := &hbrt.HbHash{
		Keys:   make([]hbrt.Value, len(dh.Keys)),
		Values: make([]hbrt.Value, len(dh.Values)),
	}
	copy(result.Keys, dh.Keys)
	copy(result.Values, dh.Values)
	for i, sk := range sh.Keys {
		result.Set(sk, sh.Values[i])
	}
	t.RetVal(hbrt.MakeHashFrom(result))
}

// JSONTYPE(cJSON) → "object"|"array"|"string"|"number"|"boolean"|"null"|"invalid"
func JsonType(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	s := strings.TrimSpace(t.Local(1).AsString())
	if s == "" {
		t.RetString("invalid")
		return
	}
	switch s[0] {
	case '{':
		t.RetString("object")
	case '[':
		t.RetString("array")
	case '"':
		t.RetString("string")
	case 't', 'f':
		t.RetString("boolean")
	case 'n':
		t.RetString("null")
	default:
		if (s[0] >= '0' && s[0] <= '9') || s[0] == '-' {
			t.RetString("number")
		} else {
			t.RetString("invalid")
		}
	}
}

// JSONVALID(cJSON) → lValid
func JsonValid(t *hbrt.Thread) {
	t.Frame(1, 0)
	defer t.EndProc()
	t.RetBool(json.Valid([]byte(t.Local(1).AsString())))
}

// JSONHTTPGET(cURL [, nTimeout]) → {"status":n, "body":c, "error":c}
func JsonHttpGet(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	url := t.Local(1).AsString()
	timeout := 30
	if nParams >= 2 && !t.Local(2).IsNil() {
		timeout = t.Local(2).AsInt()
	}
	client := &http.Client{Timeout: time.Duration(timeout) * time.Second}
	resp, err := client.Get(url)
	if err != nil {
		t.RetVal(makeHttpResult(0, "", err.Error()))
		return
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	t.RetVal(makeHttpResult(resp.StatusCode, string(body), ""))
}

// JSONHTTPPOST(cURL, xBody [, nTimeout]) → {"status":n, "body":c, "error":c}
func JsonHttpPost(t *hbrt.Thread) {
	nParams := t.ParamCount()
	t.Frame(nParams, 0)
	defer t.EndProc()
	url := t.Local(1).AsString()
	bodyVal := t.Local(2)
	timeout := 30
	if nParams >= 3 && !t.Local(3).IsNil() {
		timeout = t.Local(3).AsInt()
	}
	var bodyStr string
	if bodyVal.IsString() {
		bodyStr = bodyVal.AsString()
	} else {
		data, _ := json.Marshal(valueToGo(bodyVal))
		bodyStr = string(data)
	}
	client := &http.Client{Timeout: time.Duration(timeout) * time.Second}
	resp, err := client.Post(url, "application/json", strings.NewReader(bodyStr))
	if err != nil {
		t.RetVal(makeHttpResult(0, "", err.Error()))
		return
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	t.RetVal(makeHttpResult(resp.StatusCode, string(body), ""))
}

func makeHttpResult(status int, body, errMsg string) hbrt.Value {
	h := &hbrt.HbHash{
		Keys:   []hbrt.Value{hbrt.MakeString("status"), hbrt.MakeString("body"), hbrt.MakeString("error")},
		Values: []hbrt.Value{hbrt.MakeInt(status), hbrt.MakeString(body), hbrt.MakeString(errMsg)},
	}
	return hbrt.MakeHashFrom(h)
}

// === Conversion: Five Value ↔ Go interface{} ===

func valueToGo(v hbrt.Value) interface{} {
	if v.IsNil() {
		return nil
	}
	if v.IsLogical() {
		return v.AsBool()
	}
	if v.IsNumInt() {
		return v.AsNumInt()
	}
	if v.IsNumeric() {
		return v.AsNumDouble()
	}
	if v.IsString() {
		return v.AsString()
	}
	if v.IsArray() {
		arr := v.AsArray()
		result := make([]interface{}, len(arr.Items))
		for i, item := range arr.Items {
			result[i] = valueToGo(item)
		}
		return result
	}
	if v.IsHash() {
		h := v.AsHash()
		result := make(map[string]interface{}, len(h.Keys))
		for i := range h.Keys {
			result[h.Keys[i].AsString()] = valueToGo(h.Values[i])
		}
		return result
	}
	return nil
}

func goToValue(v interface{}) hbrt.Value {
	if v == nil {
		return hbrt.MakeNil()
	}
	switch val := v.(type) {
	case bool:
		return hbrt.MakeBool(val)
	case float64:
		if val == float64(int64(val)) {
			return hbrt.MakeNumInt(int64(val))
		}
		return hbrt.MakeDouble(val, 0, 0)
	case string:
		return hbrt.MakeString(val)
	case []interface{}:
		items := make([]hbrt.Value, len(val))
		for i, item := range val {
			items[i] = goToValue(item)
		}
		return hbrt.MakeArrayFrom(items)
	case map[string]interface{}:
		h := &hbrt.HbHash{
			Keys:   make([]hbrt.Value, 0, len(val)),
			Values: make([]hbrt.Value, 0, len(val)),
		}
		for k, v := range val {
			h.Keys = append(h.Keys, hbrt.MakeString(k))
			h.Values = append(h.Values, goToValue(v))
		}
		return hbrt.MakeHashFrom(h)
	}
	return hbrt.MakeNil()
}