// Copyright (C) 2026 Dcntrlized
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

// Package config is the complete, environment-driven runtime configuration of
// the license bot. The binary takes no arguments: the container image carries
// no secrets and the deployment decides everything through the environment.
package config

import (
	"fmt"
	"os"
	"strings"
)

// Config is the complete runtime configuration of the bot.
type Config struct {
	// GiteaURL is the instance base URL the bot calls, e.g. http://gitea:3000
	// on an instance whose Gitea shares this Docker daemon. Deliberately
	// configured here instead of taken from webhook payloads: the payload's
	// clone_url follows the instance ROOT_URL, which may be stale.
	GiteaURL string
	// PublicURL is the instance URL a *human* should follow, used only for the
	// links in the bot's PR comments. On an instance reached over the internal
	// alias (GITEA_URL=http://gitea:3000) that alias is not resolvable from a
	// browser, so the comment must link the public name instead. Defaults to
	// GiteaURL.
	PublicURL string
	// Token is a bot-account token with write access to the target repositories.
	// It lives only in this process's environment -- never in a workflow.
	Token string
	// WebhookSecret verifies X-Gitea-Signature on incoming webhook deliveries.
	// Webhooks are the only trigger, so this is required.
	WebhookSecret string
	// Repos is the allowlist of owner/name repositories the bot may touch.
	Repos []string
	// Listen is the HTTP listen address (webhook + health route).
	Listen string
	// BotName/BotEmail identify the licensing commit's committer.
	BotName  string
	BotEmail string
	// Holder is passed to addlicense -c.
	Holder string
	// AddlicenseBin is the addlicense executable (in PATH by default).
	AddlicenseBin string
	// WorkRoot is where per-PR git worktrees are created.
	WorkRoot string
	// DryRun inspects and comments but never commits or pushes.
	DryRun bool
	// CommentMarker identifies the bot's own PR comments so they can be
	// replaced (deleted and reposted, never edited in place: Gitea keeps a
	// comment's position, so an edited message stays buried in the timeline).
	CommentMarker string
	// StatusContext is the commit-status context the bot posts and the merge
	// gate requires. It must match the branch-protection string byte for byte.
	StatusContext string
}

// FromEnv builds the configuration from the process environment.
func FromEnv() (Config, error) {
	c := Config{
		GiteaURL:      strings.TrimRight(env("GITEA_URL", ""), "/"),
		PublicURL:     strings.TrimRight(env("GITEA_PUBLIC_URL", ""), "/"),
		Token:         os.Getenv("GITEA_TOKEN"),
		WebhookSecret: os.Getenv("WEBHOOK_SECRET"),
		Repos:         splitList(os.Getenv("REPOS")),
		Listen:        env("LISTEN", ":8080"),
		BotName:       env("BOT_NAME", "Dcntrlized Auto CopyLeft Bot"),
		BotEmail:      env("BOT_EMAIL", "copyleft+bot@dcntrlized.org"),
		Holder:        env("HOLDER", "Dcntrlized"),
		AddlicenseBin: env("ADDLICENSE_BIN", "addlicense"),
		WorkRoot:      env("WORK_ROOT", os.TempDir()),
		DryRun:        truthy(os.Getenv("DRY_RUN")),
		CommentMarker: env("COMMENT_MARKER", "<!-- dcntrlized-copyleft-bot -->"),
		StatusContext: env("STATUS_CONTEXT", "license-bot / addlicense"),
	}

	if c.Token == "" {
		return c, fmt.Errorf("GITEA_TOKEN is required")
	}
	if len(c.Repos) == 0 {
		return c, fmt.Errorf("REPOS is required (comma-separated owner/name list)")
	}
	if c.WebhookSecret == "" {
		return c, fmt.Errorf("WEBHOOK_SECRET is required: webhooks are the only trigger")
	}
	if c.PublicURL == "" {
		c.PublicURL = c.GiteaURL
	}
	return c, nil
}

// Allows reports whether repo (owner/name) is on the allowlist.
func (c Config) Allows(repo string) bool {
	for _, r := range c.Repos {
		if strings.EqualFold(r, repo) {
			return true
		}
	}
	return false
}

func env(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

func truthy(v string) bool {
	return v == "1" || strings.EqualFold(v, "true") || strings.EqualFold(v, "yes")
}

func splitList(v string) []string {
	var out []string
	for _, p := range strings.Split(v, ",") {
		if p = strings.TrimSpace(p); p != "" {
			out = append(out, p)
		}
	}
	return out
}