package buildfile

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

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

// ErrNoParent is raised when there is an instruction but has no parent section
var ErrNoParent = errors.New("missing parent section")

// 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 map[string]*[]instruction.T
}

type execStatus struct {
	name    string
	start   time.Time
	stop    time.Time
	stopped bool
	err     error
}
type tableSection struct {
	name         string
	instructions []execStatus
}

var reSection = regexp.MustCompile(`(?m)^\[\s*([a-z0-9_-]+)\s*\]$`)

// 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(map[string]*[]instruction.T),
	}

	// add each line as instruction
	l, reader := 0, bufio.NewReader(buildfile)
	eof := false
	var section *[]instruction.T = nil // current section
	for {
		l++
		if eof {
			break
		}

		// 1. read line until end
		line, err := reader.ReadString('\n')
		if err == io.EOF {
			if len(line) > 0 {
				eof = true
			} else {
				break
			}
		} else if err != nil {
			return nil, LineError{l, err}
		}
		line = strings.Trim(line, " \t\r\n")

		// 2. ignore newline & comments
		if len(line) < 1 || strings.ContainsAny(line[0:1], "#;") {
			continue
		}

		// 3. section
		if match := reSection.FindStringSubmatch(line); len(match) > 1 {
			// already in section
			sec := make([]instruction.T, 0)
			section = &sec
			r.Content[match[1]] = section

			continue
		}

		// 4. fail if no parent section
		if section == nil {
			return nil, ErrNoParent
		}

		// 5. create instruction
		inst, err := instruction.Parse(line)
		if err != nil {
			return nil, LineError{l, err}
		}

		// add to list
		*section = append(*section, inst)

	}

	return r, nil
}

// Execute the current buildfile instruction by instruction
// if <dryRun> is set to TRUE, run on dry-run mode
func (r *Reader) Execute(_dryRun ...bool) error {

	dryRun := true
	if len(_dryRun) < 1 || !_dryRun[0] {
		dryRun = false
	}

	// 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)
	// }
	refresh := make(chan bool, 1)
	wg := new(sync.WaitGroup)
	wgstatus := new(sync.WaitGroup)

	// 1. create status table + extract [pre] section if one
	table := make([]tableSection, 0)
	index := make(map[string]int, 0)

	var pre *[]instruction.T = nil
	var preTable *tableSection = nil

	for secname, sec := range r.Content {

		tableSec := tableSection{
			name:         secname,
			instructions: make([]execStatus, len(*sec), len(*sec)+1),
		}

		// for each instruction
		for i, inst := range *sec {
			tableSec.instructions[i].name = inst.Raw()
		}

		table = append(table, tableSec)
		index[secname] = len(table) - 1

		// [pre] section
		if secname == "pre" {
			pre = sec
			preTable = &tableSec
		}

		// add one section
		wg.Add(len(*sec))

	}

	// 2. launch status updater
	wgstatus.Add(1)
	go status(table, refresh, wgstatus)

	// 3. launch [pre] (it set)
	if pre != nil {
		execSection(pre, *r.Context, preTable, dryRun, refresh, wg)
		time.Sleep(time.Second * 2)
	}

	// 4. launch each other section
	for secname, sec := range r.Content {
		// do not launch pre again
		if secname == "pre" {
			continue
		}
		i, ok := index[secname]
		if !ok {
			continue
		}
		go execSection(sec, *r.Context, &table[i], dryRun, refresh, wg)
	}

	wg.Wait()
	close(refresh)
	wgstatus.Wait()

	return nil
}

func execSection(section *[]instruction.T, ctx instruction.ExecutionContext, tsec *tableSection, dryRun bool, refresher chan<- bool, wg *sync.WaitGroup) {

	for i, inst := range *section {
		tsec.instructions[i].start = time.Now()
		var err error = nil
		if dryRun {
			_, err = inst.DryRun(ctx)
		} else {
			_, err = inst.Exec(ctx)

		}
		tsec.instructions[i].stop = time.Now()
		tsec.instructions[i].stopped = true
		tsec.instructions[i].err = err
		refresher <- true
		wg.Done()
	}

}

func status(table []tableSection, refresher <-chan bool, wg *sync.WaitGroup) {

	for opened := true; true; _, opened = <-refresher {

		// 1. clean screen
		fmt.Printf("\033[H\033[2J")

		// 2. for each section
		for _, sec := range table {

			fmt.Printf("\n[ %s ]\n", sec.name)

			// 3. for each instruction
			for i, inst := range sec.instructions {

				if !inst.stopped {
					clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(0, inst.name)))
					fmt.Printf("%s\n", clifmt.Color(33, "processing"))
					continue
				}

				if inst.err != nil {
					clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(0, inst.name)))
					fmt.Printf("%s\n", clifmt.Color(31, inst.err.Error()))
					continue
				} else {
					clifmt.Align(fmt.Sprintf("(%d) %s", i, clifmt.Color(34, inst.name)))
					fmt.Printf("%ss\n", clifmt.Color(32, fmt.Sprintf("%.2f", inst.stop.Sub(inst.start).Seconds())))
				}

			}
		}

		if !opened {
			break
		}

	}

	wg.Done()

}