package errors

import (
	"fmt"
	"os"
	"path/filepath"

	"git.akyoto.dev/cli/q/src/build/fs"
	"git.akyoto.dev/cli/q/src/build/token"
)

// Error is a compiler error at a given line and column.
type Error struct {
	Err      error
	File     *fs.File
	Stack    string
	Position int
}

// New generates an error message at the current token position.
// The error message is clickable in popular editors and leads you
// directly to the faulty file at the given line and position.
func New(err error, file *fs.File, position int) *Error {
	return &Error{
		Err:      err,
		File:     file,
		Position: position,
		Stack:    Stack(),
	}
}

// Error generates the string representation.
func (e *Error) Error() string {
	path := e.File.Path
	cwd, err := os.Getwd()

	if err == nil {
		relativePath, err := filepath.Rel(cwd, e.File.Path)

		if err == nil {
			path = relativePath
		}
	}

	line := 1
	column := 1
	lineStart := -1

	for _, t := range e.File.Tokens {
		if t.Position >= e.Position {
			column = e.Position - lineStart
			break
		}

		if t.Kind == token.NewLine {
			lineStart = t.Position
			line++
		}
	}

	return fmt.Sprintf("%s:%d:%d: %s\n\n%s", path, line, column, e.Err, e.Stack)
}

// Unwrap returns the wrapped error.
func (e *Error) Unwrap() error {
	return e.Err
}