// Package config reads the optional ticktock config file. tock owns data;
// this only tunes the grid's presentation (slot size, window, default project).
package config

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

// Config controls grid presentation. Zero value is not valid; use Default.
type Config struct {
	SlotMinutes int
	GridStart   string
	GridEnd     string
	Project     string
}

// Default returns the documented fallbacks used when config is absent.
func Default() Config {
	return Config{SlotMinutes: 30, GridStart: "07:00", GridEnd: "21:00", Project: ""}
}

// raw mirrors the on-disk JSON; pointers distinguish "absent" from "zero".
type raw struct {
	SlotMinutes *int    `json:"slot_minutes"`
	GridStart   *string `json:"grid_start"`
	GridEnd     *string `json:"grid_end"`
	Project     *string `json:"project"`
}

// Load reads ~/.config/ticktock/config.json, falling back to defaults.
func Load() Config {
	home, err := os.UserHomeDir()
	if err != nil {
		return Default()
	}
	return LoadFrom(filepath.Join(home, ".config", "ticktock", "config.json"))
}

// LoadFrom merges the JSON at path over Default(). Any read/parse error, or a
// missing key, leaves that field at its default. SlotMinutes floors at 5.
func LoadFrom(path string) Config {
	c := Default()
	b, err := os.ReadFile(path)
	if err != nil {
		return c
	}
	var r raw
	if err := json.Unmarshal(b, &r); err != nil {
		return c
	}
	if r.SlotMinutes != nil {
		c.SlotMinutes = *r.SlotMinutes
	}
	if r.GridStart != nil {
		c.GridStart = *r.GridStart
	}
	if r.GridEnd != nil {
		c.GridEnd = *r.GridEnd
	}
	if r.Project != nil {
		c.Project = *r.Project
	}
	if c.SlotMinutes < 5 {
		c.SlotMinutes = 5
	}
	return c
}