package data

import java.awt.Desktop
import java.io.File
import java.net.URI
import java.net.URLEncoder

// Name reserved for the app-level /reload command (ChannelWindow.kt handles it directly,
// before alias lookup even runs) - kept here too so a line in aliases.txt can never define
// an alias that would shadow it.
private const val RESERVED_RELOAD = "reload"

private val defaultAliasesContent = """
    # wIRC alias commands. One alias per line: /name = type:target
    #   path:X   opens X (a file or folder) in Explorer
    #   url:X    opens X in the default browser
    #   run:X    launches X as a process
    # {arg} in the target is replaced with whatever text follows the command.
    /c = path:C:\
    /blog = url:https://bloggin.space
    /url = url:{arg}
""".trimIndent() + "\n"

/**
 * Global (not per-server/per-channel) alias command table, loaded once at app startup
 * (see Main.kt) and shared by every ChannelWindow's command router.
 *
 * aliases.txt is bundled into the install directory by build.gradle.kts's
 * appResourcesRootDir (see installerResources/aliases.txt), which puts it somewhere under
 * Program Files - normally UAC-protected. On [init], this repository figures out whether
 * that bundled copy can actually be hand-edited in place; if not, it falls back to a
 * writable copy under %APPDATA%\wIRC instead and uses that from then on.
 */
object AliasRepository {

    private var aliases: Map<String, String> = emptyMap()

    lateinit var activeFile: File
        private set

    fun init() {
        activeFile = resolveAliasFile()
        aliases = loadAliases(activeFile)
        println("[AliasRepository] Using aliases file: ${activeFile.absolutePath} (${aliases.size} aliases loaded)")
    }

    /** Re-reads aliases.txt from the currently active path. Returns the number of aliases loaded. */
    fun reload(): Int {
        aliases = loadAliases(activeFile)
        return aliases.size
    }

    /** True if [command] (without the leading '/') is an alias - those run locally, no server needed. */
    fun hasAlias(command: String): Boolean {
        val key = command.lowercase()
        return key != RESERVED_RELOAD && key in aliases
    }

    /**
     * Returns true if [command] (without the leading '/') matched a known alias and its
     * action was run - callers should treat that as "handled, don't fall through to IRC
     * command handling". Returns false for unknown commands (including the reserved
     * "reload" name, which this repository never loads as an alias).
     */
    fun tryRunAlias(command: String, args: String): Boolean {
        val key = command.lowercase()
        if (key == RESERVED_RELOAD) return false
        val action = aliases[key] ?: return false
        runAction(action, args)
        return true
    }

    private fun runAction(action: String, args: String) {
        val colonIdx = action.indexOf(':')
        if (colonIdx < 0) return
        val type = action.substring(0, colonIdx).trim()
        val rawTarget = action.substring(colonIdx + 1).trim()

        // URL targets need their {arg} substitution percent-encoded - java.net.URI's
        // single-String constructor does strict RFC 2396 parsing and throws
        // URISyntaxException on a raw space (e.g. "/src alexis road" against
        // "url:...?search={arg}" produces "...?search=alexis road", which URI() rejects
        // outright). That exception used to be swallowed by the catch below with only a
        // println - invisible in a windowed app with no attached console, so a multi-word
        // arg looked like the alias silently did nothing. path/run targets are real
        // filesystem paths or process args, so they're left unencoded - a space there is
        // literal, not a URL delimiter.
        val substitutedArg = if (type == "url") encodeArgForUrl(args) else args
        val target = if (rawTarget.contains("{arg}")) rawTarget.replace("{arg}", substitutedArg) else rawTarget
        if (target.isBlank()) return

        try {
            when (type) {
                "path" -> Desktop.getDesktop().open(File(target))
                "url" -> Desktop.getDesktop().browse(URI(target))
                // Routed through "cmd /c start" (same launch path as double-clicking in
                // Explorer or the Run dialog) rather than exec'd directly. A direct
                // ProcessBuilder(target).start() calls CreateProcess, which does NOT honor
                // an exe's embedded "requireAdministrator" manifest - it just fails with
                // CreateProcess error 740 (ERROR_ELEVATION_REQUIRED). "start" goes through
                // ShellExecute instead, which shows the same UAC prompt a normal launch
                // would. This also preserves bare-name resolution via Windows' App Paths
                // registry / PATH - not guaranteed to work for every app, since it depends
                // on that app having registered itself with Windows.
                "run" -> ProcessBuilder("cmd", "/c", "start", "\"\"", target).start()
                else -> println("[AliasRepository] Unknown alias action type '$type' in \"$action\"")
            }
        } catch (e: Exception) {
            println("[AliasRepository] Failed to run alias action \"$action\" (target=\"$target\"): ${e.message}")
        }
    }

    // Percent-encodes only what would actually break URI parsing or misrepresent the
    // argument (whitespace, quotes, non-ASCII, etc.), matching the standard
    // application/x-www-form-urlencoded convention of encoding spaces as '+' (the ticket's
    // expected "search=alexis+road" output). Structural/reserved URI characters
    // (: / ? # & = etc.) are passed through unencoded so an alias like "/url = url:{arg}"
    // still works when {arg} is itself a full URL rather than a query value.
    private fun encodeArgForUrl(args: String): String {
        val safe = "-_.~:/?#[]@!$&'()*+,;=%"
        val sb = StringBuilder()
        for (c in args) {
            when {
                c == ' ' -> sb.append('+')
                c.isLetterOrDigit() && c.code < 128 -> sb.append(c)
                c in safe -> sb.append(c)
                else -> sb.append(URLEncoder.encode(c.toString(), "UTF-8"))
            }
        }
        return sb.toString()
    }

    private fun loadAliases(file: File): Map<String, String> {
        if (!file.exists()) return emptyMap()
        val result = mutableMapOf<String, String>()
        file.readLines().forEach { line ->
            val trimmed = line.trim()
            if (trimmed.isEmpty() || trimmed.startsWith("#")) return@forEach
            val eqIdx = trimmed.indexOf('=')
            if (eqIdx < 0) return@forEach
            val name = trimmed.substring(0, eqIdx).trim().removePrefix("/").lowercase()
            val action = trimmed.substring(eqIdx + 1).trim()
            if (name.isEmpty() || action.isEmpty() || name == RESERVED_RELOAD) return@forEach
            result[name] = action
        }
        return result
    }

    private fun resolveAliasFile(): File {
        val appDataFile = File(File(appDataRoot(), "wIRC"), "aliases.txt")
        val resourcesDirProp = System.getProperty("compose.application.resources.dir")

        if (resourcesDirProp != null) {
            val bundled = File(resourcesDirProp, "aliases.txt")
            if (bundled.exists()) {
                return if (isDirectoryWritable(bundled.parentFile)) {
                    // Program Files write protection isn't active (or this isn't an
                    // installed build) - edit the bundled copy in place, as intended.
                    bundled
                } else {
                    println(
                        "[AliasRepository] ${bundled.absolutePath} is not writable " +
                            "(Program Files protection) - falling back to ${appDataFile.absolutePath}"
                    )
                    if (!appDataFile.exists()) {
                        appDataFile.parentFile?.mkdirs()
                        // Best-effort: carry over the bundled starter content. If even
                        // reading it fails (locked file, odd ACLs, etc.) fall back to the
                        // built-in default rather than leaving init() to crash the app.
                        try {
                            bundled.copyTo(appDataFile, overwrite = false)
                        } catch (e: Exception) {
                            println("[AliasRepository] Couldn't copy bundled aliases.txt (${e.message}) - writing default starter content instead")
                            appDataFile.writeText(defaultAliasesContent)
                        }
                    }
                    appDataFile
                }
            }
        }

        // Dev run (no installer resources dir set) or bundled file missing - seed a
        // starter file directly under %APPDATA% so the feature still works from source.
        if (!appDataFile.exists()) {
            appDataFile.parentFile?.mkdirs()
            appDataFile.writeText(defaultAliasesContent)
        }
        return appDataFile
    }

    private fun appDataRoot(): File =
        System.getenv("APPDATA")?.let { File(it) }
            ?: File(System.getProperty("user.home"), "AppData/Roaming")

    // File.canWrite() can lie (or simply be unavailable) on some Windows ACL setups, so
    // this confirms writability the same way the file will actually be edited: a real
    // write followed by cleanup.
    private fun isDirectoryWritable(dir: File?): Boolean {
        if (dir == null) return false
        return try {
            val probe = File(dir, ".wirc_write_test_${System.nanoTime()}.tmp")
            probe.writeText("")
            probe.delete()
            true
        } catch (e: Exception) {
            false
        }
    }
}