package buildstep

import (
	"encoding/json"
	"fmt"
	"os"

	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
)

// CapacitySetting is the build modules' setting of each node's build capacity (novox/hq ADR 0525 §5): `<node>=<asks at
// once>` pairs separated by commas, as the builder's was (ADR 0485 §1). Each build module declares it with
// DefaultCapacities as its default, and the controller lays it into the module's settings file.
const CapacitySetting = "capacity"

// DefaultCapacities is the setting's default, the builder's before R4g: the control-node (novox) and the laptop (g14)
// build nothing.
const DefaultCapacities = "shanks=3,ace=2,g14=0,novox=0"

// NodeCapacity is node's build capacity, read from the module's settings file at path at every call, so a change takes
// effect at the next pull; with no path it reads fallback. A node the setting does not name runs one ask at a time (as
// the builder's did). A file or a setting that cannot be read gives 0 and says why: pulling on a setting nobody can read
// could build on a node that must not.
func NodeCapacity(path, fallback, node string, logf func(string, ...any)) func() int {
	say := func(format string, args ...any) {
		if logf != nil {
			logf(format, args...)
		}
	}
	return func() int {
		setting := fallback
		if path != "" {
			raw, err := os.ReadFile(path)
			if err != nil {
				say("the build capacity cannot be read, so %s pulls nothing: %v", node, err)
				return 0
			}
			var s map[string]any
			if err := json.Unmarshal(raw, &s); err != nil {
				say("the settings file %s is not JSON, so %s pulls nothing: %v", path, node, err)
				return 0
			}
			setting, _ = s[CapacitySetting].(string)
		}
		caps, err := buildrun.ParseCapacity(setting)
		if err != nil {
			say("%v, so %s pulls nothing", fmt.Errorf("the build capacity: %w", err), node)
			return 0
		}
		return (&buildrun.Places{Capacity: caps}).CapacityOf(node)
	}
}