package main

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

	"gitea/internal/forgehttp"
)

// The forge as this bundle reaches it: its own HTTP interface on the machine, as the forge's admin account
// (internal/forgehttp, shared with the forge bundle beside it). Basic authentication, so this bundle mints
// nothing and keeps nothing: the TypeScript bundle's token is its own.

// Forge is the forge's HTTP interface.
type Forge struct {
	forgehttp.Client
	Owner string // the package registry's owner, as the seat serves it
}

// ForgeFromEnv is the forge as the manifest hands it to this bundle.
func ForgeFromEnv() (*Forge, error) {
	c, missing := forgehttp.FromEnv()
	f := &Forge{Client: c, Owner: os.Getenv("MESH_NPM_OWNER")}
	if f.Owner == "" {
		missing = append(missing, "MESH_NPM_OWNER")
	}
	if len(missing) > 0 {
		return nil, fmt.Errorf("the forge cannot be reached: %s not set by the manifest", strings.Join(missing, ", "))
	}
	return f, nil
}

// errNotFound is the forge answering 404.
var errNotFound = forgehttp.ErrNotFound

// maxBody is the largest answer read from the forge.
const maxBody = forgehttp.MaxBody

// do sends one request without a body and answers the body; 404 is errNotFound.
func (f *Forge) do(ctx context.Context, method, path string) ([]byte, error) {
	return f.Do(ctx, method, path, nil, maxBody)
}

// PackageVersion is one version of one package, as the forge lists it.
type PackageVersion struct {
	Name      string    `json:"name"`
	Version   string    `json:"version"`
	CreatedAt time.Time `json:"created_at"`
}

const pageSize = 50

// Packages is every npm package version of the owner, all pages.
func (f *Forge) Packages(ctx context.Context) ([]PackageVersion, error) {
	var all []PackageVersion
	for page := 1; page <= 1000; page++ {
		var batch []PackageVersion
		path := fmt.Sprintf("/api/v1/packages/%s?type=npm&page=%d&limit=%d", url.PathEscape(f.Owner), page, pageSize)
		if err := f.GetJSON(ctx, path, &batch); err != nil {
			return nil, err
		}
		all = append(all, batch...)
		if len(batch) < pageSize {
			return all, nil
		}
	}
	return nil, errors.New("the forge listed more than 1000 pages of packages; stopped rather than read for ever")
}

func (f *Forge) versionPath(name, version string) string {
	return fmt.Sprintf("/api/v1/packages/%s/npm/%s/%s", url.PathEscape(f.Owner), url.PathEscape(name), url.PathEscape(version))
}

// Size is the bytes of one version's files.
func (f *Forge) Size(ctx context.Context, name, version string) (int64, error) {
	var files []struct {
		Size int64 `json:"size"`
	}
	if err := f.GetJSON(ctx, f.versionPath(name, version)+"/files", &files); err != nil {
		return 0, err
	}
	var total int64
	for _, file := range files {
		total += file.Size
	}
	return total, nil
}

// DistTags is the dist-tags of one package, from the registry's own metadata.
func (f *Forge) DistTags(ctx context.Context, name string) (map[string]string, error) {
	var meta struct {
		DistTags map[string]string `json:"dist-tags"`
	}
	path := fmt.Sprintf("/api/packages/%s/npm/%s", url.PathEscape(f.Owner), url.PathEscape(name))
	if err := f.GetJSON(ctx, path, &meta); err != nil {
		return nil, err
	}
	return meta.DistTags, nil
}

// Delete removes one version from the registry.
func (f *Forge) Delete(ctx context.Context, name, version string) error {
	_, err := f.do(ctx, http.MethodDelete, f.versionPath(name, version))
	return err
}

// Repository is one repository on the forge, as far as reading its manifests needs.
type Repository struct {
	FullName      string `json:"full_name"`
	DefaultBranch string `json:"default_branch"`
	Empty         bool   `json:"empty"`
}

// Repositories is every repository the admin sees.
func (f *Forge) Repositories(ctx context.Context) ([]Repository, error) {
	var all []Repository
	for page := 1; page <= 1000; page++ {
		var found struct {
			Data []Repository `json:"data"`
		}
		if err := f.GetJSON(ctx, fmt.Sprintf("/api/v1/repos/search?page=%d&limit=%d", page, pageSize), &found); err != nil {
			return nil, err
		}
		all = append(all, found.Data...)
		if len(found.Data) < pageSize {
			return all, nil
		}
	}
	return nil, errors.New("the forge listed more than 1000 pages of repositories; stopped rather than read for ever")
}

func repoPath(fullName string) string {
	owner, name, _ := strings.Cut(fullName, "/")
	return url.PathEscape(owner) + "/" + url.PathEscape(name)
}

// Files is every file path on a branch, all pages of the forge's tree.
func (f *Forge) Files(ctx context.Context, repo Repository) ([]string, error) {
	var paths []string
	seen := 0
	for page := 1; page <= 1000; page++ {
		var tree struct {
			Tree []struct {
				Path string `json:"path"`
				Type string `json:"type"`
			} `json:"tree"`
			Truncated  bool `json:"truncated"`
			TotalCount int  `json:"total_count"`
		}
		path := fmt.Sprintf("/api/v1/repos/%s/git/trees/%s?recursive=true&page=%d&per_page=1000",
			repoPath(repo.FullName), url.PathEscape(repo.DefaultBranch), page)
		if err := f.GetJSON(ctx, path, &tree); err != nil {
			return nil, err
		}
		for _, e := range tree.Tree {
			if e.Type == "blob" {
				paths = append(paths, e.Path)
			}
		}
		seen += len(tree.Tree)
		if len(tree.Tree) == 0 || !tree.Truncated && (tree.TotalCount == 0 || seen >= tree.TotalCount) {
			return paths, nil
		}
	}
	return nil, fmt.Errorf("%s has more than 1000 pages of files; not read whole", repo.FullName)
}

// Raw is one file's content on the repository's default branch.
func (f *Forge) Raw(ctx context.Context, repo Repository, file string) ([]byte, error) {
	escaped := strings.Split(file, "/")
	for i := range escaped {
		escaped[i] = url.PathEscape(escaped[i])
	}
	return f.do(ctx, http.MethodGet, fmt.Sprintf("/api/v1/repos/%s/raw/%s?ref=%s",
		repoPath(repo.FullName), strings.Join(escaped, "/"), url.QueryEscape(repo.DefaultBranch)))
}