package caster

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	errors2 "github.com/abelith/spellbook/internal/errors"
	"github.com/abelith/spellbook/internal/models"
	"github.com/google/shlex"
	"os/exec"
	"text/template"
	"time"
)

type SpellCaster struct{}

func (sc *SpellCaster) Cast(ctx context.Context, cast models.SpellCast) (models.CastResult, error) {
	args, err := renderSpell(cast)
	if err != nil {
		return models.CastResult{}, err
	}

	cmd := exec.CommandContext(ctx, args[0], args[1:]...)
	cmd.Stdin = cast.Stdin
	cmd.Stdout = cast.Stdout
	cmd.Stderr = cast.Stderr

	start := time.Now()
	err = cmd.Run()
	duration := time.Since(start)

	res := models.CastResult{
		Duration: duration,
	}

	if err != nil {
		var exitErr *exec.ExitError
		if errors.As(err, &exitErr) {
			res.ExitCode = exitErr.ExitCode()
			res.Err = err
			return res, nil
		}
		return res, fmt.Errorf("%w: %w", errors2.ErrFailedToCast, err)
	}

	res.ExitCode = 0
	return res, nil
}

func renderSpell(cast models.SpellCast) ([]string, error) {
	tmpl, err := template.New(cast.Spell.Name).Option("missingkey=error").Parse(cast.Spell.Spell)
	if err != nil {
		return nil, err
	}

	buf := bytes.NewBuffer(nil)
	if err := tmpl.Execute(buf, cast.Args); err != nil {
		return nil, err
	}

	return shlex.Split(buf.String())
}