package tui

import (
	"errors"
	"fmt"
	"strconv"
	"time"

	"github.com/charmbracelet/bubbles/textinput"
	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
)

type FormField struct {
	textinput.Model
	label string
}

func (ff FormField) Update(msg tea.Msg) (FormField, tea.Cmd) {
	field, cmd := ff.Model.Update(msg)
	ff.Model = field
	return ff, cmd
}

func newTimestampField(label string) FormField {
	f := FormField{
		Model: textinput.New(),
		label: label,
	}
	f.Validate = func(s string) error {
		if _, err := time.Parse(time.DateTime, s); err != nil {
			return fmt.Errorf("timestamps must be written like \"%s\"", time.DateTime)
		}
		return nil
	}
	return f
}

func newOptionalTimestampField(label string) FormField {
	f := FormField{
		Model: textinput.New(),
		label: label,
	}
	f.Validate = func(s string) error {
		if s == "" {
			return nil
		}
		if _, err := time.Parse(time.DateTime, s); err != nil {
			return fmt.Errorf("timestamps must be written like \"%s\"", time.DateTime)
		}
		return nil
	}
	return f
}

func newOptionalFloatField(label string) FormField {
	f := FormField{
		Model: textinput.New(),
		label: label,
	}
	f.Validate = func(s string) error {
		if s == "" {
			return nil
		}
		_, err := strconv.ParseFloat(s, 64)
		if err != nil {
			return errors.New("numerical values only")
		}
		return nil
	}
	return f
}

type Form struct {
	fields []FormField
	selIdx int
	err    error

	SelectedStyle   *lipgloss.Style
	UnselectedStyle *lipgloss.Style
}

func NewForm(fields []FormField) Form {
	return Form{fields: fields}
}

func (ff Form) Error() error {
	for _, field := range ff.fields {
		if field.Err != nil {
			return field.Err
		}
	}
	return nil
}

func NewEntryEditorForm() Form {
	form := NewForm([]FormField{
		newTimestampField("Start time"),
		newOptionalTimestampField("End time"),
		{Model: textinput.New(), label: "Client"},
		{Model: textinput.New(), label: "Project"},
		{Model: textinput.New(), label: "Description"},
		newOptionalFloatField("Hourly Rate"),
	})
	form.SelectedStyle = &modalFocusedInputStyle
	form.UnselectedStyle = &modalBlurredInputStyle
	return form
}

func NewClientForm() Form {
	form := NewForm([]FormField{
		{Model: textinput.New(), label: "Name"},
		{Model: textinput.New(), label: "Email"},
		newOptionalFloatField("Hourly Rate"),
	})
	form.SelectedStyle = &modalFocusedInputStyle
	form.UnselectedStyle = &modalBlurredInputStyle
	return form
}

func NewProjectForm() Form {
	form := NewForm([]FormField{
		{Model: textinput.New(), label: "Name"},
		{Model: textinput.New(), label: "Client"},
		newOptionalFloatField("Hourly Rate"),
	})
	form.SelectedStyle = &modalFocusedInputStyle
	form.UnselectedStyle = &modalBlurredInputStyle
	return form
}

func (ff Form) Update(msg tea.Msg) (Form, tea.Cmd) {
	if msg, ok := msg.(tea.KeyMsg); ok {
		switch msg.String() {
		case "tab":
			ff.fields[ff.selIdx].Blur()
			ff.selIdx = (ff.selIdx + 1) % len(ff.fields)
			return ff, ff.fields[ff.selIdx].Focus()
		case "shift+tab":
			ff.fields[ff.selIdx].Blur()
			ff.selIdx--
			if ff.selIdx < 0 {
				ff.selIdx += len(ff.fields)
			}
			return ff, ff.fields[ff.selIdx].Focus()
		}
	}

	field, cmd := ff.fields[ff.selIdx].Update(msg)
	ff.fields[ff.selIdx] = field
	return ff, cmd
}

func (ff Form) View() string {
	content := ""

	if ff.err != nil {
		content += errorStyle.Render(ff.err.Error()) + "\n\n"
	}

	for i, field := range ff.fields {
		if i > 0 {
			content += "\n\n"
		}
		content += field.label + ":\n"

		style := ff.UnselectedStyle
		if i == ff.selIdx {
			style = ff.SelectedStyle
		}
		if style != nil {
			content += style.Render(field.View())
		} else {
			content += field.View()
		}

		if field.Err != nil {
			content += "\n" + errorStyle.Render(field.Err.Error())
		}
	}
	return content
}

var (
	modalFocusedInputStyle = lipgloss.NewStyle().
				Border(lipgloss.DoubleBorder()).
				BorderForeground(lipgloss.Color("238"))
	modalBlurredInputStyle = lipgloss.NewStyle().
				Border(lipgloss.NormalBorder()).
				BorderForeground(lipgloss.Color("238"))
	errorStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("196"))
)