// Package status records per-repo deploy state (which commit is in production /
// preview) so the forge can badge commits. Backed by a single JSON file.
package status

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sync"
)

// Entry is the commit + URL for a deploy state.
type Entry struct {
	Commit string `json:"commit"`
	URL    string `json:"url"`
}

// Repo holds the current production + preview pointers for one repo.
type Repo struct {
	Production Entry `json:"production"`
	Preview    Entry `json:"preview"`
}

// Store is a concurrency-safe JSON-backed status store.
type Store struct {
	path string
	mu   sync.Mutex
	data map[string]Repo
}

// Open loads the store from path (creating an empty one if absent).
func Open(path string) (*Store, error) {
	s := &Store{path: path, data: map[string]Repo{}}
	b, err := os.ReadFile(path)
	if err == nil {
		_ = json.Unmarshal(b, &s.data)
	} else if !os.IsNotExist(err) {
		return nil, err
	}
	return s, nil
}

// Set updates a repo's production or preview pointer and persists.
func (s *Store) Set(repo, state, commit, url string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	r := s.data[repo]
	switch state {
	case "prod", "production":
		r.Production = Entry{Commit: commit, URL: url}
	case "preview":
		r.Preview = Entry{Commit: commit, URL: url}
	default:
		return nil // ignore unknown states
	}
	s.data[repo] = r
	return s.persist()
}

// Badge returns the deploy state of a commit ("production"|"preview"|"") and its
// URL. Empty state means unverified.
func (s *Store) Badge(repo, commit string) (state, url string) {
	if commit == "" {
		return "", ""
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	r := s.data[repo]
	switch commit {
	case r.Production.Commit:
		return "production", r.Production.URL
	case r.Preview.Commit:
		return "preview", r.Preview.URL
	}
	return "", ""
}

// Has reports whether a repo has any recorded deploy status.
func (s *Store) Has(repo string) bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	r, ok := s.data[repo]
	return ok && (r.Production.Commit != "" || r.Preview.Commit != "")
}

func (s *Store) persist() error {
	if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
		return err
	}
	b, err := json.MarshalIndent(s.data, "", "  ")
	if err != nil {
		return err
	}
	tmp := s.path + ".tmp"
	if err := os.WriteFile(tmp, b, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, s.path)
}