// google_sheets — 讀取或寫入 Google 試算表
// 透過 host function 呼叫 Google Sheets API
//
//go:build tinygo

package main

import (
	"encoding/json"
	"io"
	"os"
	"unsafe"
)

//go:wasmimport u6u http_request
func hostHttpRequest(
	urlPtr uintptr, urlLen uint32,
	methodPtr uintptr, methodLen uint32,
	headersPtr uintptr, headersLen uint32,
	bodyPtr uintptr, bodyLen uint32,
	outPtr uintptr, outLenPtr uintptr,
) uint32

type Input struct {
	SpreadsheetID string              `json:"spreadsheet_id"`
	Range         string              `json:"range"`
	Action        string              `json:"action"`
	Values        [][]json.RawMessage `json:"values"`
	AccessToken   string              `json:"access_token"`
}

func main() {
	raw, err := io.ReadAll(os.Stdin)
	if err != nil {
		writeError("failed to read stdin: " + err.Error())
		return
	}
	var input Input
	if err := json.Unmarshal(raw, &input); err != nil {
		writeError("invalid input JSON: " + err.Error())
		return
	}
	if input.SpreadsheetID == "" {
		writeError("spreadsheet_id 必填")
		return
	}
	if input.Range == "" {
		writeError("range 必填")
		return
	}
	if input.AccessToken == "" {
		writeError("access_token 必填")
		return
	}

	action := input.Action
	if action == "" {
		action = "read"
	}

	headers := map[string]string{
		"Authorization": "Bearer " + input.AccessToken,
		"Content-Type":  "application/json",
	}
	headersJSON, _ := json.Marshal(headers)

	var apiURL, method, bodyStr string

	switch action {
	case "read":
		apiURL = "https://sheets.googleapis.com/v4/spreadsheets/" + input.SpreadsheetID + "/values/" + input.Range
		method = "GET"
		bodyStr = ""
	case "write":
		apiURL = "https://sheets.googleapis.com/v4/spreadsheets/" + input.SpreadsheetID + "/values/" + input.Range + "?valueInputOption=RAW"
		method = "PUT"
		bodyData, _ := json.Marshal(map[string]interface{}{
			"range":          input.Range,
			"majorDimension": "ROWS",
			"values":         input.Values,
		})
		bodyStr = string(bodyData)
	default:
		writeError("不支援的 action: " + action)
		return
	}

	urlBytes := []byte(apiURL)
	methodBytes := []byte(method)
	bodyBytes := []byte(bodyStr)
	if len(bodyBytes) == 0 {
		bodyBytes = []byte{}
	}

	outBuf := make([]byte, 65536)
	var outLen uint32

	var bodyPtr uintptr
	if len(bodyBytes) > 0 {
		bodyPtr = uintptr(unsafe.Pointer(&bodyBytes[0]))
	}

	result := hostHttpRequest(
		uintptr(unsafe.Pointer(&urlBytes[0])), uint32(len(urlBytes)),
		uintptr(unsafe.Pointer(&methodBytes[0])), uint32(len(methodBytes)),
		uintptr(unsafe.Pointer(&headersJSON[0])), uint32(len(headersJSON)),
		bodyPtr, uint32(len(bodyBytes)),
		uintptr(unsafe.Pointer(&outBuf[0])), uintptr(unsafe.Pointer(&outLen)),
	)

	if result != 0 {
		writeError("Google Sheets API 呼叫失敗")
		return
	}

	responseStr := string(outBuf[:outLen])
	var responseData interface{}
	if err := json.Unmarshal([]byte(responseStr), &responseData); err != nil {
		responseData = responseStr
	}

	out, _ := json.Marshal(map[string]interface{}{
		"success": true,
		"data": map[string]interface{}{
			"values": responseData,
			"range":  input.Range,
		},
	})
	os.Stdout.Write(out)
}

func writeError(msg string) {
	out, _ := json.Marshal(map[string]interface{}{"success": false, "error": msg})
	os.Stdout.Write(out)
}