// kbdb_get — 從 KBDB 讀 block（GET /blocks?page_name=... 或 GET /blocks/:id）
// thin wrapper：透過 host function http_request 呼叫 KBDB API
//
//go:build tinygo

package main

import (
	"encoding/json"
	"io"
	"os"
	"strconv"
	"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 {
	KBDBUrl  string `json:"kbdb_url"`  // optional
	APIKey   string `json:"api_key"`   // 必填
	BlockID  string `json:"block_id"`  // 與 page_name 二擇一
	PageName string `json:"page_name"` // 與 block_id 二擇一
	Limit    int    `json:"limit"`     // optional, default 50
}

var dummy [1]byte

func safePtr(b []byte) (uintptr, uint32) {
	if len(b) == 0 {
		return uintptr(unsafe.Pointer(&dummy[0])), 0
	}
	return uintptr(unsafe.Pointer(&b[0])), uint32(len(b))
}

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

// urlEncode：簡易 query string encoder（只處理 KBDB 會用到的字元）
// 避免引入 net/url（白名單外）
func urlEncode(s string) string {
	var out []byte
	for i := 0; i < len(s); i++ {
		c := s[i]
		if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') ||
			c == '-' || c == '_' || c == '.' || c == '~' {
			out = append(out, c)
		} else {
			const hex = "0123456789ABCDEF"
			out = append(out, '%', hex[c>>4], hex[c&0x0f])
		}
	}
	return string(out)
}

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.APIKey == "" {
		writeError("api_key 必填")
		return
	}
	if input.BlockID == "" && input.PageName == "" {
		writeError("block_id 或 page_name 必填其一")
		return
	}

	kbdbURL := input.KBDBUrl
	if kbdbURL == "" {
		kbdbURL = "https://kbdb.finally.click"
	}

	limit := input.Limit
	if limit <= 0 {
		limit = 50
	}

	// 構造 URL：block_id 模式走 /blocks/:id（單一），page_name 模式走 /blocks?page_name=...&limit=N
	var url string
	if input.BlockID != "" {
		url = kbdbURL + "/blocks/" + urlEncode(input.BlockID)
	} else {
		url = kbdbURL + "/blocks?page_name=" + urlEncode(input.PageName) +
			"&limit=" + strconv.Itoa(limit)
	}

	headers := map[string]string{
		"Authorization": "Bearer " + input.APIKey,
	}
	headersBytes, _ := json.Marshal(headers)

	method := "GET"
	urlBytes := []byte(url)
	methodBytes := []byte(method)

	outBuf := make([]byte, 1<<20) // 1MB（list 可能很大）
	var outLen uint32

	urlPtr, urlLen := safePtr(urlBytes)
	methodPtr, methodLen := safePtr(methodBytes)
	headersPtr, headersLenU := safePtr(headersBytes)
	bodyPtr, bodyLenU := safePtr(nil)

	result := hostHttpRequest(
		urlPtr, urlLen,
		methodPtr, methodLen,
		headersPtr, headersLenU,
		bodyPtr, bodyLenU,
		uintptr(unsafe.Pointer(&outBuf[0])), uintptr(unsafe.Pointer(&outLen)),
	)

	if result != 0 {
		writeError("KBDB GET request failed (host_http_request returned non-zero)")
		return
	}

	respStr := string(outBuf[:outLen])

	// 解析回應
	if input.BlockID != "" {
		// 單一 block：KBDB 直接回 block 物件，包成 array 給下游 foreach
		var block map[string]interface{}
		if err := json.Unmarshal([]byte(respStr), &block); err != nil {
			writeError("KBDB returned non-JSON: " + respStr)
			return
		}
		if _, hasErr := block["error"]; hasErr {
			out, _ := json.Marshal(map[string]interface{}{
				"success": false, "error": block["error"],
			})
			os.Stdout.Write(out)
			return
		}
		out, _ := json.Marshal(map[string]interface{}{
			"success": true,
			"blocks":  []map[string]interface{}{block},
			"count":   1,
		})
		os.Stdout.Write(out)
		return
	}

	// page_name 列表模式：KBDB 回 {"blocks": [...], "count": N}
	var listResp struct {
		Blocks []map[string]interface{} `json:"blocks"`
		Count  int                      `json:"count"`
		Error  interface{}              `json:"error"`
	}
	if err := json.Unmarshal([]byte(respStr), &listResp); err != nil {
		writeError("KBDB returned non-JSON: " + respStr)
		return
	}
	if listResp.Error != nil {
		out, _ := json.Marshal(map[string]interface{}{
			"success": false, "error": listResp.Error,
		})
		os.Stdout.Write(out)
		return
	}
	out, _ := json.Marshal(map[string]interface{}{
		"success": true,
		"blocks":  listResp.Blocks,
		"count":   listResp.Count,
	})
	os.Stdout.Write(out)
}