package stonelog

import (
	"encoding/json"
	"fmt"
	"log"
	"math/rand"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"time"
)

// logEntry represents the structure for a single log entry.
// Time is the timestamp of the log entry in RFC3339 format.
// Level specifies the severity level of the log message.
// Caller describes the source file and line generating the log.
// Message contains the actual log details or description.
type logEntry struct {
	Time    string `json:"time"`
	Level   string `json:"level"`
	Caller  string `json:"caller"`
	Message string `json:"message"`
}

// StoneLevel represents the severity level of logging categories.
type StoneLevel int

// String returns the string representation of the StoneLevel.
func (l StoneLevel) String() string {
	return stoneLevelNames[l]
}

// Color returns the color code associated with the StoneLevel.
func (l StoneLevel) Color() string {
	return levelColors[l]
}

// TRACE represents the trace log level.
// DEBUG represents the debug log level.
// INFO represents the info log level.
// WARN represents the warning log level.
// ERROR represents the error log level.
// FATAL represents the fatal log level.
// PANIC represents the panic log level.
const (
	TRACE StoneLevel = iota
	DEBUG
	INFO
	WARN
	ERROR
	FATAL
	PANIC
)

// stoneLevelNames maps StoneLevel constants to their string representations.
var stoneLevelNames = map[StoneLevel]string{
	TRACE: "TRACE",
	DEBUG: "DEBUG",
	INFO:  "INFO",
	WARN:  "WARN",
	ERROR: "ERROR",
	FATAL: "FATAL",
	PANIC: "PANIC",
}

// ANSI color codes for terminal text formatting.
const (
	colorReset   = "\033[0m"
	colorRed     = "\033[31m"
	colorGreen   = "\033[32m"
	colorYellow  = "\033[33m"
	colorMagenta = "\033[35m"
	colorCyan    = "\033[36m"
	colorWhite   = "\033[37m"
)

// levelColors maps StoneLevel constants to their corresponding color codes.
var levelColors = map[StoneLevel]string{
	TRACE: colorWhite,
	DEBUG: colorCyan,
	INFO:  colorGreen,
	WARN:  colorYellow,
	ERROR: colorRed,
	FATAL: colorMagenta,
	PANIC: colorRed + "\033[1m",
}

// stoneLogger is a logger instance for logging stone-related operations.
// currentLogLevel indicates the active logging level for stoneLogger.
// disableCharacterSuffixes disables suffixes in log outputs when true.
var (
	stoneLogger              *log.Logger
	currentLogLevel          StoneLevel
	useJSON                  bool
	callerFrameDepth         = 3
	disableCharacterSuffixes bool
)

// InitStoneLog initializes the logging system with the specified parameters.
// level sets the logging severity level threshold.
// jsonMode determines whether logs should be output in JSON format.
// disableSuffixes disables character suffixes in log messages.
func InitStoneLog(level StoneLevel, jsonMode, disableSuffixes bool) {
	currentLogLevel = level
	stoneLogger = log.New(os.Stdout, "", 0)
	useJSON = jsonMode
	disableCharacterSuffixes = disableSuffixes
}

// SetLogLevel sets the current log level to the specified StoneLevel.
func SetLogLevel(level StoneLevel) {
	if level < TRACE || level > PANIC {
		return
	}

	currentLogLevel = level
	Observation("Log level set to %v", level)
}

// Trace logs a message at the TRACE using the specified format and arguments.
func Trace(format string, args ...interface{}) {
	logMessage(TRACE, format, args...)
}

// Debug logs a message at the DEBUG level using the provided format and arguments.
func Debug(format string, args ...interface{}) {
	logMessage(DEBUG, format, args...)
}

// Observation logs a message at the INFO level with optional formatting arguments.
func Observation(format string, args ...interface{}) {
	logMessage(INFO, format, args...)
}

// Hypothesis logs a message with WARN level using the provided format and arguments.
func Hypothesis(format string, args ...interface{}) {
	logMessage(WARN, format, args...)
}

// Failure logs a message at the ERROR level using the provided format and arguments.
func Failure(format string, args ...interface{}) {
	logMessage(ERROR, format, args...)
}

// Meltdown logs a message at the FATAL level and terminates the program.
func Meltdown(format string, args ...interface{}) {
	logMessage(FATAL, format, args...)
}

// Panic logs a message with PANIC severity and terminates the application.
func Panic(format string, args ...interface{}) {
	logMessage(PANIC, format, args...)
}

// getCallerInfo retrieves the file name and line number of the caller.
// It returns the information in the format "file:line" or "unknown:0" on failure.
func getCallerInfo() string {
	_, file, line, ok := runtime.Caller(callerFrameDepth)
	if !ok {
		return "unknown:0"
	}
	return filepath.Base(file) + ":" + strconv.Itoa(line)
}

// logMessage handles the logging of messages with varying severity levels.
// If the log level is below the configured threshold, it is ignored.
// Formats the message, adds a random prefix, and appends optional suffixes.
// Converts the output to JSON format if enabled or applies a custom formatter.
// Executes fatal or panic behaviors when specified severity levels are met.
func logMessage(level StoneLevel, format string, args ...interface{}) {
	if level < FATAL && currentLogLevel > level {
		return
	}

	msg := fmt.Sprintf(format, args...)
	msg = getRandomPrefix(level) + " " + msg

	// Determine if success or failure quote is needed
	isSuccess := level <= WARN

	if !disableCharacterSuffixes {
		msg += getRandomQuote(isSuccess)
	}

	var formatted string

	if useJSON {
		caller := getCallerInfo()

		entry := logEntry{
			Time:    time.Now().UTC().Format(time.RFC3339),
			Level:   level.String(),
			Caller:  caller,
			Message: msg,
		}
		jsonData, _ := json.Marshal(entry)
		formatted = string(jsonData)
	} else {
		formatted = stoneFormat(level, msg)
	}

	// Handle special logging behaviors for FATAL and PANIC
	switch level {
	case FATAL:
		stoneLogger.Fatalln(formatted)
	case PANIC:
		stoneLogger.Panicln(formatted)
	default:
		stoneLogger.Println(formatted)
	}
}

// getRandomPrefix returns a random prefix string based on the given StoneLevel.
// It selects from predefined lists corresponding to the severity of the level.
func getRandomPrefix(level StoneLevel) string {
	// Map StoneLevel to their respective prefix slices
	prefixMap := map[StoneLevel][]string{
		TRACE: stoneTracePrefixes,
		DEBUG: stoneDebugPrefixes,
		INFO:  stoneInfoPrefixes,
		WARN:  stoneWarnPrefixes,
		ERROR: stoneErrorPrefixes,
		FATAL: stonePanicPrefixes,
		PANIC: stonePanicPrefixes,
	}

	prefixes := prefixMap[level]

	// Select and return a random prefix
	return prefixes[rand.Intn(len(prefixes))]
}

// getRandomQuote returns a random character quote based on success or failure.
// The isSuccess parameter indicates if the quote is for a success (true) or failure.
func getRandomQuote(isSuccess bool) string {
	if isSuccess {
		idx := rand.Intn(len(characterSuccessQuoteSuffixes))
		return characterSuccessQuoteSuffixes[idx]
	} else {
		idx := rand.Intn(len(characterFailQuoteSuffixes))
		return characterFailQuoteSuffixes[idx]
	}
}

// stoneFormat formats a log message with level, timestamp, caller, and color.
func stoneFormat(level StoneLevel, msg string) string {
	now := time.Now().UTC().Format(time.RFC3339)
	caller := getCallerInfo()
	return fmt.Sprintf(
		"%s%s [%s] [%s] %s%s", level.Color(), now, level.String(), caller, msg,
		colorReset,
	)
}