// Code generated by @openmeter/typespec-go. DO NOT EDIT.

package openmeter

import (
	"fmt"
	"iter"
	"net/url"
	"strconv"
)

const defaultListPageSize = 100
const maxPages = 10_000

// PageParams selects a numbered page.
type PageParams struct {
	Size   *int
	Number *int
}

// CursorPageParams selects a cursor page.
type CursorPageParams struct {
	Size   *int
	After  *string
	Before *string
}

type PageMeta struct {
	Number int `json:"number"`
	Size   int `json:"size"`
	Total  int `json:"total"`
}

type PaginatedMeta struct {
	Page PageMeta `json:"page"`
}

func addPageParams(q url.Values, page *PageParams) {
	if page == nil {
		return
	}
	if page.Size != nil {
		setDeepObjectString(q, "page", "size", strconv.Itoa(*page.Size))
	}
	if page.Number != nil {
		setDeepObjectString(q, "page", "number", strconv.Itoa(*page.Number))
	}
}

func addCursorPageParams(q url.Values, page *CursorPageParams) {
	if page == nil {
		return
	}
	if page.Size != nil {
		setDeepObjectString(q, "page", "size", strconv.Itoa(*page.Size))
	}
	if page.After != nil {
		setDeepObjectString(q, "page", "after", *page.After)
	}
	if page.Before != nil {
		setDeepObjectString(q, "page", "before", *page.Before)
	}
}

func paginate[T any](start *PageParams, fetch func(page, size int) ([]T, int, error)) iter.Seq2[T, error] {
	return func(yield func(T, error) bool) {
		page, size := 1, defaultListPageSize
		if start != nil {
			if start.Number != nil {
				page = *start.Number
			}
			if start.Size != nil {
				size = *start.Size
			}
		}
		seen := 0
		for fetched := 0; fetched < maxPages; fetched++ {
			data, total, err := fetch(page, size)
			if err != nil {
				var zero T
				yield(zero, err)
				return
			}
			for _, item := range data {
				if !yield(item, nil) {
					return
				}
			}
			seen += len(data)
			if len(data) == 0 || (total > 0 && seen >= total) {
				return
			}
			page++
		}
		var zero T
		yield(zero, fmt.Errorf("openmeter: pagination did not terminate within %d pages", maxPages))
	}
}

func paginateCursor[T any](start *CursorPageParams, fetch func(after, before *string, size int) ([]T, *string, *string, error)) iter.Seq2[T, error] {
	return func(yield func(T, error) bool) {
		size := defaultListPageSize
		var after, before *string
		if start != nil {
			after = start.After
			before = start.Before
			if after != nil && before != nil {
				var zero T
				yield(zero, fmt.Errorf("openmeter: cursor pagination cannot use both after and before"))
				return
			}
			if start.Size != nil {
				size = *start.Size
			}
		}
		reverse := before != nil
		for fetched := 0; fetched < maxPages; fetched++ {
			data, next, previous, err := fetch(after, before, size)
			if err != nil {
				var zero T
				yield(zero, err)
				return
			}
			for _, item := range data {
				if !yield(item, nil) {
					return
				}
			}
			if reverse {
				if previous == nil || *previous == "" || len(data) == 0 {
					return
				}
				before = previous
			} else {
				if next == nil || *next == "" || len(data) == 0 {
					return
				}
				after = next
			}
		}
		var zero T
		yield(zero, fmt.Errorf("openmeter: cursor pagination did not terminate within %d pages", maxPages))
	}
}