// Copyright (c) 2026 Lark Technologies Pte. Ltd.
// SPDX-License-Identifier: MIT

package client

import (
	"fmt"
	"io"

	"github.com/larksuite/cli/internal/core"
	"github.com/larksuite/cli/internal/output"
)

// PaginationOptions contains pagination control options.
type PaginationOptions struct {
	PageLimit int           // max pages to fetch; 0 = unlimited (default: 10)
	PageDelay int           // ms, default 200
	Identity  core.Identity // identity passed to checkErr; defaults to AsUser when empty
}

func mergePagedResults(w io.Writer, results []interface{}) interface{} {
	if len(results) == 0 {
		return map[string]interface{}{}
	}

	firstMap, ok := results[0].(map[string]interface{})
	if !ok {
		return map[string]interface{}{"pages": results}
	}

	data, ok := firstMap["data"].(map[string]interface{})
	if !ok {
		return map[string]interface{}{"pages": results}
	}

	arrayField := output.FindArrayField(data)
	if arrayField == "" {
		return map[string]interface{}{"pages": results}
	}

	var merged []interface{}
	for _, r := range results {
		if rm, ok := r.(map[string]interface{}); ok {
			if d, ok := rm["data"].(map[string]interface{}); ok {
				if items, ok := d[arrayField].([]interface{}); ok {
					merged = append(merged, items...)
				}
			}
		}
	}

	fmt.Fprintf(w, "[pagination] merged %d pages, %d total items\n", len(results), len(merged))

	mergedData := make(map[string]interface{})
	for k, v := range data {
		mergedData[k] = v
	}
	mergedData[arrayField] = merged

	// Surface the last page's real has_more so callers can detect truncation
	// when --page-limit stops the loop before the API is exhausted. Page tokens
	// are intentionally dropped: the merged view is an aggregate, not a resume
	// cursor — to fetch more, re-run with a larger --page-limit.
	lastHasMore := false
	if lastMap, ok := results[len(results)-1].(map[string]interface{}); ok {
		if lastData, ok := lastMap["data"].(map[string]interface{}); ok {
			lastHasMore, _ = lastData["has_more"].(bool)
		}
	}
	mergedData["has_more"] = lastHasMore
	delete(mergedData, "page_token")
	delete(mergedData, "next_page_token")

	result := make(map[string]interface{})
	for k, v := range firstMap {
		result[k] = v
	}
	result["data"] = mergedData

	return result
}