package program

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"git.gophernest.net/azpect/TextEditor/internal/core"
	"git.gophernest.net/azpect/TextEditor/internal/editor"
	tea "github.com/charmbracelet/bubbletea"
)

type ProgramBuilder struct {
	model *editor.Model
	opts  []tea.ProgramOption
}

func NewProgramBuilder() *ProgramBuilder {
	return &ProgramBuilder{
		model: &editor.Model{},
		opts:  []tea.ProgramOption{},
	}
}

// ProgramBuilder.FileProgram: Sets the internal state of the builder to the required
// state to start the program (editor) with a filename. This is what will happen when
// a user runs 'gim <filename>'.
func (p *ProgramBuilder) FileProgram(filename string) *ProgramBuilder {
	// Only difference: open the file
	ext := filepath.Ext(filename)

	file, err := os.Open(filename)
	notFound := errors.Is(err, os.ErrNotExist)
	if err != nil && !notFound {
		// TODO: Handle this
		panic(fmt.Errorf("Failed to find file: %w", err))
	}
	if file != nil {
		defer file.Close()
	}

	buf := core.NewBufferBuilder().
		WithType(core.FileBuffer).
		WithFilename(filename).
		WithFiletype(ext).
		Listed().
		Build()

	win := core.NewWindowBuilder().
		WithBuffer(&buf).
		WithOptions(core.NewDefaultWinOptions()).
		Build()

	p.model = editor.NewModelBuilder().
		AddBuffer(&buf).
		AddWindow(&win).
		WithActiveWindowId(win.Id).
		Build()

	// If we did not find the file, all we need to do is set the filename and type
	if notFound {
		return p
	}

	// Otherwise we have to create everything, then read the file (since we need settings)
	// COPIED FROM `internal/command/handlers.go`
	var lines []string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		line = strings.TrimSuffix(line, "\r")

		// BUG: This is bad, we don't want to this, but we have to
		cleaned := strings.ReplaceAll(line, "\t", strings.Repeat(" ", p.model.Settings().TabStop))
		lines = append(lines, cleaned)
	}

	// Only setting lines if we found some
	if len(lines) > 0 {
		p.model.ActiveBuffer().SetLines(lines)
	}

	return p
}

// ProgramBuilder.EmptyProgram: Sets the internal state of the builder to the required
// state to start the program (editor) in the current directory. This is what will
// happen when a user runs 'gim'.
func (p *ProgramBuilder) EmptyProgram() *ProgramBuilder {
	buf := core.NewBufferBuilder().
		ReadOnly().
		Build()

	win := core.NewWindowBuilder().
		WithBuffer(&buf).
		WithOptions(core.NewDefaultWinOptions()).
		Build()

	p.model = editor.NewModelBuilder().
		AddBuffer(&buf).
		AddWindow(&win).
		WithActiveWindowId(win.Id).
		Build()

	return p
}

// ProgramBuilder.WithOpt: Add an option to the list of options that will be used when
// the program is built.
func (p *ProgramBuilder) WithOpt(opt tea.ProgramOption) *ProgramBuilder {
	p.opts = append(p.opts, opt)
	return p
}

// ProgramBuilder.Build: Build and return the configured tea.Program instance.
func (p *ProgramBuilder) Build() *tea.Program {
	return tea.NewProgram(p.model, p.opts...)
}