package main

import (
	"fmt"
	"os"

	"git.maximhutz.com/max/lambda/internal/cli"
	"git.maximhutz.com/max/lambda/internal/config"
	"git.maximhutz.com/max/lambda/internal/engine"
	"git.maximhutz.com/max/lambda/internal/explanation"
	"git.maximhutz.com/max/lambda/internal/performance"
	"git.maximhutz.com/max/lambda/internal/statistics"
	"git.maximhutz.com/max/lambda/pkg/convert"
	"git.maximhutz.com/max/lambda/pkg/lambda"
	"git.maximhutz.com/max/lambda/pkg/saccharine"
)

func main() {
	// Parse CLI arguments.
	options, err := config.FromArgs()
	cli.HandleError(err)

	logger := options.GetLogger()
	logger.Info("using program arguments", "args", os.Args)
	logger.Info("parsed CLI options", "options", options)

	// Get input.
	input, err := options.Source.Extract()
	cli.HandleError(err)

	// Parse code into syntax tree.
	ast, err := saccharine.Parse(input)
	cli.HandleError(err)
	logger.Info("parsed syntax tree", "tree", ast)

	// Compile expression to lambda calculus.
	compiled := convert.SaccharineToLambda(ast)
	logger.Info("compiled λ expression", "tree", lambda.Stringify(compiled))

	// Create reduction engine.
	process := engine.New(options, &compiled)

	// If the user selected to track CPU performance, attach a profiler to the
	// process.
	if options.Profile != "" {
		profiler := performance.Track(options.Profile)
		process.On("start", profiler.Start)
		process.On("end", profiler.End)
	}

	// If the user selected to produce a step-by-step explanation, attach an
	// observer here.
	if options.Explanation {
		explanation.Track(process)
	}

	// If the user opted to track statistics, attach a tracker here, too.
	if options.Statistics {
		statistics := statistics.Track()
		process.On("start", statistics.Start)
		process.On("step", statistics.Step)
		process.On("end", statistics.End)
	}

	// If the user selected for verbose debug logs, attach a reduction tracker.
	if options.Verbose {
		process.On("step", func() {
			logger.Info("reduction", "tree", lambda.Stringify(compiled))
		})
	}

	process.Run()

	// Return the final reduced result.
	fmt.Println(lambda.Stringify(compiled))
}