package buildfile

import (
	"bufio"
	"errors"
	"fmt"
	"github.com/xdrm-brackets/nix-amer/internal/clifmt"
	"github.com/xdrm-brackets/nix-amer/internal/instruction"
	"io"
	"strings"
	"time"
)

// ErrNullContext is raised when the given context is nil
var ErrNullContext = errors.New("null context")

// Reader is the buildfile reader
type Reader struct {
	// Context is the linux distribution-specified execution context (package manager, service manager, etc)
	Context *instruction.ExecutionContext
	// Content is the instruction list
	Content []instruction.T
}

// NewReader creates a new reader for the specified build file and linux distribution
func NewReader(ctx *instruction.ExecutionContext, buildfile io.Reader) (*Reader, error) {

	// fail on null context
	if ctx == nil {
		return nil, ErrNullContext
	}

	r := &Reader{
		Context: ctx,
		Content: make([]instruction.T, 0),
	}

	// add each line as instruction
	l, reader := 0, bufio.NewReader(buildfile)
	for {
		l++

		// read line until end
		line, err := reader.ReadString('\n')
		if err == io.EOF {
			break
		} else if err != nil {
			return nil, LineError{l, err}
		}
		line = strings.Trim(line, " \t\r\n")

		// ignore newline & comments
		if len(line) < 1 || strings.ContainsAny(line[0:1], "[#;") {
			continue
		}

		// turn into instruction
		inst, err := instruction.Parse(line)
		if err != nil {
			return nil, LineError{l, err}
		}

		// add to list
		r.Content = append(r.Content, inst)

	}

	return r, nil
}

// Execute the current buildfile instruction by instruction
func (r *Reader) Execute() error {

	// 1. update package list
	// err := r.Context.PackageManager.Fetch()
	// if err != nil {
	// 	return fmt.Errorf("cannot fetch packages | %s", err)
	// }

	// // 2. upgrade packages
	// err = r.Context.PackageManager.Upgrade()
	// if err != nil {
	// 	return fmt.Errorf("cannot upgrade | %s", err)
	// }

	// 3. exec each instruction
	for i, inst := range r.Content {
		clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(0, inst.Raw())))
		fmt.Printf("%s", clifmt.Color(33, "processing"))

		start := time.Now()

		_, err := inst.Exec(*r.Context)
		if err != nil {
			fmt.Printf("\r")
			clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(0, inst.Raw())))
			fmt.Printf("%s          \n", clifmt.Color(31, err.Error()))
			continue
		} else {
			fmt.Printf("\r")
			clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(34, inst.Raw())))
			fmt.Printf("%ss         \n", clifmt.Color(32, fmt.Sprintf("%.2f", time.Now().Sub(start).Seconds())))
		}
	}

	return nil
}