package main

import (
	"context"
	"errors"
	"fmt"
	"net/url"
	"regexp"
	"strings"

	"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 npm-registry bundle beside it).

// Forge is the forge's HTTP interface.
type Forge struct {
	forgehttp.Client
}

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

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

// maxBody is the largest JSON answer read from the forge; maxArchive the largest archive code search reads.
const (
	maxBody    = forgehttp.MaxBody
	maxArchive = 64 << 20
)

// Refused is a refusal of policy or of an argument, in the words the caller sees.
type Refused struct{ msg string }

func (r *Refused) Error() string { return r.msg }

func refuse(format string, a ...any) error { return &Refused{fmt.Sprintf(format, a...)} }

var nameShape = regexp.MustCompile(`^[A-Za-z0-9_][A-Za-z0-9_.-]*$`)

// repoPath is /api/v1/repos/{owner}/{repo} for names that cannot become another path.
func repoPath(owner, repo string) (string, error) {
	for _, v := range [][2]string{{"owner", owner}, {"name", repo}} {
		if !nameShape.MatchString(v[1]) || v[1] == "." || v[1] == ".." {
			return "", refuse("%q is not a repository %s", v[1], v[0])
		}
	}
	return "/api/v1/repos/" + owner + "/" + repo, nil
}

// segments encodes a value that is several path segments — a branch like fix/1-x, a file's path — refusing
// any segment that could make the request another path: empty, `.` or `..`, or holding `?`, `#`, `%`, `\`
// or a control character (the same rule as the TypeScript bundle's pathSegments, guard.ts).
func segments(what, value string) (string, error) {
	parts := strings.Split(value, "/")
	for i, p := range parts {
		if p == "" || p == "." || p == ".." || strings.ContainsAny(p, "?#%\\") || strings.IndexFunc(p, func(r rune) bool { return r < 0x20 || r == 0x7f }) >= 0 {
			return "", refuse("%q is not a %s this tool puts in a path. Nothing was sent", value, what)
		}
		parts[i] = url.PathEscape(p)
	}
	return strings.Join(parts, "/"), nil
}

// Repo is what the tools read of a repository.
type Repo struct {
	FullName      string `json:"full_name"`
	DefaultBranch string `json:"default_branch"`
	Empty         bool   `json:"empty"`
}

// Protection is one branch protection rule, as far as covering a branch goes.
type Protection struct {
	RuleName   string `json:"rule_name"`
	BranchName string `json:"branch_name"`
}

func (p Protection) name() string {
	if p.RuleName != "" {
		return p.RuleName
	}
	return p.BranchName
}

// Branch is one branch with the commit it points at.
type Branch struct {
	Name   string `json:"name"`
	Commit struct {
		ID string `json:"id"`
	} `json:"commit"`
}

// branch is the named branch, nil when the forge has none of that name.
func (f *Forge) branch(ctx context.Context, repo, name string) (*Branch, error) {
	seg, err := segments("branch", name)
	if err != nil {
		return nil, err
	}
	var b Branch
	if err := f.GetJSON(ctx, repo+"/branches/"+seg, &b); err != nil {
		if errors.Is(err, errNotFound) {
			return nil, nil
		}
		return nil, err
	}
	return &b, nil
}