package assert

import (
	"fmt"
	"path/filepath"
	"runtime"
	"strings"
)

const messageFormat = `
%s:%d
assert.%s
    Expected: %v
    Actual:   %v
`

const singleValueFormat = `
%s:%d
assert.%s
    Value: %v
`

// fileInfo returns file and line information for the test caller
func fileInfo() (string, int) {
	// Skip frames: runtime.Callers, this function, assertion function, and test helper
	// This gets us to the actual test file that called the assertion
	const skip = 3
	_, file, line, ok := runtime.Caller(skip)
	if !ok {
		return "unknown_file", 0
	}

	// Extract just the filename without the full path
	fileName := filepath.Base(file)

	// If we're still not in a test file, search up the stack
	if !strings.Contains(fileName, "_test.go") {
		// Try one more frame up
		_, file, line, ok = runtime.Caller(skip + 1)
		if ok {
			fileName = filepath.Base(file)
		}
	}

	return fileName, line
}

// formatMessage formats an error message with the file location
func formatMessage(methodName string, expected, actual any) string {
	file, line := fileInfo()
	return fmt.Sprintf(messageFormat, file, line, methodName, expected, actual)
}

// formatSingleValueMessage formats an error message for single-value assertions
func formatSingleValueMessage(methodName string, value any) string {
	file, line := fileInfo()
	return fmt.Sprintf(singleValueFormat, file, line, methodName, value)
}