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

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

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

// Tracking tunes the autotrack daemon; read from config.json's `tracking`
// object. Defaults 5, 900, 15 match the Python daemon's constants.
type Tracking struct {
	PollSecs      int // fine poll → tighter boundaries, catch short switches
	IdleGraceSecs int // HID gap < this stays active; >= → idle
	MinSecs       int // drop segments shorter than this
}

// Default returns the documented fallbacks used when config is absent.
func Default() Config {
	return Config{
		SlotMinutes: 30, GridStart: "07:00", GridEnd: "21:00", Project: "",
		Tracking: Tracking{PollSecs: 5, IdleGraceSecs: 900, MinSecs: 15},
	}
}

// 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"`
	Tracking    *rawTracking `json:"tracking"`
}

type rawTracking struct {
	PollSecs      *int `json:"poll_secs"`
	IdleGraceSecs *int `json:"idle_grace_secs"`
	MinSecs       *int `json:"min_secs"`
}

// 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 r.Tracking != nil {
		if r.Tracking.PollSecs != nil {
			c.Tracking.PollSecs = *r.Tracking.PollSecs
		}
		if r.Tracking.IdleGraceSecs != nil {
			c.Tracking.IdleGraceSecs = *r.Tracking.IdleGraceSecs
		}
		if r.Tracking.MinSecs != nil {
			c.Tracking.MinSecs = *r.Tracking.MinSecs
		}
	}
	if c.SlotMinutes < 5 {
		c.SlotMinutes = 5
	}
	return c
}