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 (internal/forgehttp, shared with the
// forge bundle beside it), never as the admin account. It reads as the tools' account, whose token carries
// read:package, and writes (a publish, a remove, retention's deletion) as the packages account, whose token carries
// write:package (design 51: each holder keeps its write side as an own secret beside a read-only tool token). The
// TypeScript bundle mints and keeps both tokens (token.ts, packages-account.ts); this bundle mints nothing.

// Forge is the forge's HTTP interface.
type Forge struct {
	forgehttp.Client // reads, as the tools' account
	// Writer writes into the package registry, as the packages account; nil writes nothing.
	Writer *forgehttp.Client
	Owner  string // the package registry's owner, as the seat serves it
	// Type is the registry's package type retention reads: TypeNpm when empty, or TypeGo.
	Type string
	// Refused says whether the forge refused the write side's token (401), as the finding PackagesTokenRefused in the
	// module's findings state: the TypeScript bundle mints a new token on that key's event and clears it (no timer
	// looks at the token). Nil says nothing.
	Refused func(raised bool)
}

// PackagesTokenRefused is the finding this bundle raises when the forge refuses the packages account's token, and its
// key in the module's findings state (packages-account.ts PACKAGES_TOKEN_REFUSED watches that key).
const (
	PackagesTokenRefused    = "packages-token-refused"
	PackagesTokenRefusedKey = "seat.gitea.packages-token-refused_write"
)

// wrote is a write's answer, said on Refused: a 401 raises the finding, a write the forge took clears it.
func (f *Forge) wrote(err error) error {
	if f.Refused == nil {
		return err
	}
	var status *forgehttp.StatusError
	switch {
	case errors.As(err, &status) && status.Status == http.StatusUnauthorized:
		f.Refused(true)
	case err == nil:
		f.Refused(false)
	}
	return err
}

// The package types the retention reads: npm packages (the npm seat) and Go modules (the Go seat).
const (
	TypeNpm = "npm"
	TypeGo  = "go"
)

// typ is the package type this forge's retention reads.
func (f *Forge) typ() string {
	if f.Type == "" {
		return TypeNpm
	}
	return f.Type
}

// As is the same forge, its retention reading the package type typ.
func (f *Forge) As(typ string) *Forge {
	out := *f
	out.Type = typ
	return &out
}

// ForgeFromEnv is the forge as the manifest hands it to this bundle.
func ForgeFromEnv() (*Forge, error) {
	c, missing := forgehttp.FromEnv()
	w, writeMissing := forgehttp.WriterFromEnv()
	for _, m := range writeMissing {
		if m != "MESH_GITEA_URL" {
			missing = append(missing, m)
		}
	}
	f := &Forge{Client: c, Writer: &w, Owner: os.Getenv("MESH_NPM_OWNER"), Refused: func(raised bool) {
		finding(PackagesTokenRefused, "write", "the forge refused the package seats' write token; the module mints it afresh", raised)
	}}
	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 package version of the owner of this forge's type, 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=%s&page=%d&limit=%d", url.PathEscape(f.Owner), f.typ(), 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 f.packagePath(f.typ(), name, 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
}

// write is the registry's write side, refused when the manifest handed none.
func (f *Forge) write() (*forgehttp.Client, error) {
	if f.Writer == nil {
		return nil, errors.New("the package registry's write side is not handed to this bundle (MESH_GITEA_PACKAGES_TOKEN_FILE); nothing was written")
	}
	return f.Writer, nil
}

// Delete removes one version from the registry, as the packages account.
func (f *Forge) Delete(ctx context.Context, name, version string) error {
	w, err := f.write()
	if err != nil {
		return err
	}
	_, err = w.Do(ctx, http.MethodDelete, f.versionPath(name, version), nil, maxBody)
	return f.wrote(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)))
}