// Program history — the box half of D2 (spec §3.2). Every Go main package
// path this box has pointed live for a route, in the bake directory. A build
// whose program is in its route's history is never "the wrong program", which
// is what lets a deliberate A -> B change be rolled back to A.
package release

import (
	"encoding/json"
	"path/filepath"
	"slices"
	"strings"

	"github.com/carlosframework/platform/internal/safefile"
)

func programPath(bakeDir, host string) string {
	return filepath.Join(bakeDir, "programs", host+".json")
}

func ReadPrograms(bakeDir, host string) []string {
	if strings.ContainsAny(host, `/\`) {
		return nil
	}
	b, err := safefile.ReadFile(programPath(bakeDir, host))
	if err != nil {
		return nil
	}
	var rec struct {
		Programs []string `json:"programs"`
	}
	if json.Unmarshal(b, &rec) != nil {
		return nil
	}
	return rec.Programs
}

func RecordProgram(bakeDir, host, program string) error {
	if program == "" || strings.ContainsAny(host, `/\`) {
		return nil
	}
	have := ReadPrograms(bakeDir, host)
	if slices.Contains(have, program) {
		return nil
	}
	b, err := json.Marshal(struct {
		Schema   int      `json:"schema"`
		Programs []string `json:"programs"`
	}{1, append(have, program)})
	if err != nil {
		return err
	}
	p := programPath(bakeDir, host)
	if err := safefile.MkdirAll(filepath.Dir(p), 0o755); err != nil {
		return err
	}
	return safefile.WriteFile(p, b, 0o644)
}