import * as mri from 'mri';
import * as os from 'os';
import { getCommandDefinitionParameterValue, validateCommandDefinitionParameterValue } from './parameters';
import { ParserErrors } from './ParserErrors';
import { CliProgram } from './program';
import { CliPromptHandler, CliPromptResult } from './prompt';
import {
    CliCommandDefinition,
    CliCommandDefinitionArgument,
    CliCommandDefinitionOption,
    CliCommandDefinitionParameter,
    CliParsedCommandDefinitionArgument,
    CliParsedCommandDefinitionOption,
    CliParsedCommandHandler,
    CliProgramDefinition,
    CliRunResult,
    CliValue,
    CliValueValidatorFunction,
    ParsedCliCommand,
    ParserErrorType,
} from './types';
import { dashCase, getOptionsMriOpts, isFunction, passedOptionsToNames } from './utils';

export class Parser {
    private _parsedCommand: Partial<ParsedCliCommand>;
    private _definitionsMap: Map<string, CliCommandDefinition> = new Map();
    private _argVals: string[] = [];
    private _optionVals: { [name: string]: CliValue } = {};
    private _definitionOptions: CliCommandDefinitionOption[];
    private _commandPackage: CliProgram;
    private _passedOptions: string[] = [];
    private _parserErrors = new ParserErrors();

    constructor(
        private argv: string[] = process.argv,
        commandPackageDefinition: CliProgramDefinition,
        private runHandler: CliParsedCommandHandler,
        private errorHandler: CliParsedCommandHandler,
        private promptHandler: CliPromptHandler,
        private version: string | undefined,
        private internalOptions: CliCommandDefinitionOption[] = [],
        private showPrompts = false
    ) {
        this._commandPackage = CliProgram.create(commandPackageDefinition, internalOptions);
        if (this._commandPackage.validationErrors.length > 0) {
            throw new Error(`Invalid Command Definition: ${this._commandPackage.validationErrors.join(os.EOL)}`);
        }
        this._definitionsMap = this._commandPackage.commandsMap;
    }

    private findCommandDefinition = (name: string): CliCommandDefinition => {
        let cmdDef = this._definitionsMap.get(name);
        if (!cmdDef) {
            // if no exact match on command name, try to match on all lower case, or dash-case of command name
            const cmdDefs = Array.from(this._definitionsMap.values());
            cmdDef = cmdDefs.find(
                d =>
                    dashCase(d.name).toLowerCase() === name.toLowerCase() || d.name.toLowerCase() === name.toLowerCase()
            );
        }
        return cmdDef;
    };

    private parseCommandLine = () => {
        let offset = 2;

        // parse using root and internal options
        this._definitionOptions = this.internalOptions.concat(this._commandPackage.options || []);

        let parsedMri = mri(this.argv.slice(offset), getOptionsMriOpts(this._definitionOptions));

        // Loop thru possible command(s)
        let tryName: string;
        let name = '';
        let i = 1;
        const len = parsedMri._.length + 1;
        for (; i < len; i++) {
            tryName = parsedMri._.slice(0, i).join(' ');
            // if (this._definitionsMap.has(tryName)) {
            if (this.findCommandDefinition(tryName)) {
                name = tryName;
                offset = i + 2; // argv slicer
            }
        }

        let cmdDef = this.findCommandDefinition(name);

        if (!cmdDef) {
            if (name) {
                this.pushError('command', `Unknown Command: '${name}'`);
            } else if (this._commandPackage.defaultCommandName) {
                cmdDef = this._definitionsMap.get(this._commandPackage.defaultCommandName);
            } else if (this._commandPackage.commands.length > 0) {
                this.pushError('command', `No Command Specified`);
            }
        }

        // this._passedOptions = passedOptionsToNames(, ;
        const rawPassedOptions = Object.keys(parsedMri).filter(v => v !== '_');

        // if a command definition is identified, re-parse the command line with definition configurations
        if (cmdDef) {
            this._definitionOptions.push(...(cmdDef.options || []));
            parsedMri = mri(this.argv.slice(offset), getOptionsMriOpts(this._definitionOptions));
            this._argVals = parsedMri._;
            this._parsedCommand.command = cmdDef;
            this._parsedCommand.parsedCommandName = name;
        }

        this._passedOptions = passedOptionsToNames(rawPassedOptions, this._definitionOptions);

        // Collect parsed Options
        this._optionVals = Object.keys(parsedMri)
            .filter(v => v !== '_')
            .reduce((prev, curr) => {
                prev[curr] = parsedMri[curr];
                return prev;
            }, {});

        // Create a hash with all active options for final parsed output
        this._parsedCommand.optionDefinitions = this._definitionOptions.reduce((prev, curr) => {
            prev[curr.name] = curr;
            return prev;
        }, {});
    };

    private parseArgs = () => {
        const cmd = this.parsedCommand.command;
        const defArgs = cmd ? cmd.arguments || [] : [];
        const requiredDefArgs = defArgs.filter(a => !a.isOptional);
        const isVariadic = defArgs.length > 0 && defArgs[defArgs.length - 1].isVariadic;

        // check for too many args
        if (this._argVals.length > defArgs.length && !isVariadic) {
            this.pushError('argument', `Too many Arguments`);
        }

        // check for too few args
        if (this._argVals.length < requiredDefArgs.length) {
            // don't raise insufficient args if an option with a handler is set (ie help/version);
            if (!this.getParsedOptionCommandName()) {
                this.pushError('argument', `Insufficient arguments`);
            }
        }

        const parsedArgs: { [name: string]: CliParsedCommandDefinitionArgument } = {};
        const validateArg = (val: CliValue, arg: CliCommandDefinitionArgument) => {
            const validation = validateCommandDefinitionParameterValue(val, arg);
            if (validation !== true) {
                const msg = typeof validation === 'string' ? validation : undefined;
                this.pushError('argument', `Value for argument '${arg.name}' is invalid${msg ? `: ${msg}` : ''}`);
            }
        };
        let argValIndex = 0;
        // Loop through definition arguments, and assign each prop in definition to args value array
        for (let i = 0; i < defArgs.length; i++) {
            const defArg = defArgs[i];
            if (defArg.isVariadic) {
                // variadic arg, must be last arg, assign remainder of command line
                const vals = this._argVals.slice(argValIndex).map(a => getCommandDefinitionParameterValue(a, defArg));
                // validate each value
                vals.forEach(v => validateArg(v, defArg));
                parsedArgs[defArg.name] = {
                    ...defArg,
                    wasPassed: true,
                    value: vals,
                };
                argValIndex = this._argVals.length;
            } else if (this._argVals.length > argValIndex) {
                // still arguments from command line, assign next arg to args arry
                // assign value from command line to args array
                const val = getCommandDefinitionParameterValue(this._argVals[argValIndex], defArg);
                // validate
                validateArg(val, defArg);
                parsedArgs[defArg.name] = {
                    ...defArg,
                    wasPassed: true,
                    value: val,
                };
                argValIndex++;
            } else {
                // no more arguments on command line, assign default
                parsedArgs[defArg.name] = {
                    ...defArg,
                    wasPassed: false,
                    value: getCommandDefinitionParameterValue(undefined, defArg, false),
                };
                argValIndex++;
            }
        }

        // create args hash with just values
        const args = Object.keys(parsedArgs).reduce((prev, curr) => {
            prev[curr] = parsedArgs[curr].value;
            return prev;
        }, {});

        const transformedArgs = isFunction(cmd.transformArguments) ? cmd.transformArguments(args) : args;

        // re-assign parsed arg value from transformed args (transform could add or remove entries, so not necessarily 1:1)
        Object.keys(transformedArgs).forEach(ta => {
            if (parsedArgs[ta]) {
                parsedArgs[ta].value = transformedArgs[ta];
            }
        });

        this.parsedCommand.parsedArguments = parsedArgs;
        this.parsedCommand.arguments = transformedArgs;
    };

    private parseOptions = () => {
        const cmd = this._parsedCommand.command;
        Object.keys(this._optionVals).forEach(o => {
            if (!this._definitionOptions.find(co => co.name === o || co.flag === o || dashCase(co.name) === o)) {
                this.pushError('option', `Invalid Option: ${o}`);
            }
        });

        const parsedOptions: { [name: string]: CliParsedCommandDefinitionOption } = {};

        this._definitionOptions.forEach(o => {
            const wasPassed = this._passedOptions.indexOf(o.name) >= 0;
            parsedOptions[o.name] = {
                ...o,
                wasPassed,
                value: getCommandDefinitionParameterValue(this._optionVals[o.name], o, wasPassed),
            };
            if (wasPassed) {
                // if option set on command line, and not a boolean option, make sure there is a value
                if (o.valueType && o.valueType !== 'boolean' && !parsedOptions[o.name].value) {
                    this.pushError('option', `Value for option '${o.name}' not specified`);
                } else {
                    const validation = validateCommandDefinitionParameterValue(parsedOptions[o.name].value, o);
                    if (validation !== true) {
                        const msg = typeof validation === 'string' ? validation : undefined;
                        this.pushError('option', `Value for option '${o.name}' is invalid${msg ? `: ${msg}` : ''}`);
                    }
                }
            }
        });

        // create args hash with just values
        const options = Object.keys(parsedOptions).reduce((prev, curr) => {
            prev[curr] = parsedOptions[curr].value;
            return prev;
        }, {});

        const transformedOptions = cmd
            ? isFunction(cmd.transformOptions)
                ? cmd.transformOptions(options)
                : options
            : options;

        // re-assign parsed option value from transformed options (transform could add or remove entries, so not necessarily 1:1)
        Object.keys(transformedOptions).forEach(to => {
            if (parsedOptions[to]) {
                parsedOptions[to].value = transformedOptions[to];
            }
        });

        this._parsedCommand.parsedOptions = parsedOptions;
        this._parsedCommand.options = transformedOptions;
    };

    private pushError = (type: ParserErrorType, message: string) => {
        this._parserErrors.push(type, message);
    };

    private getEnv = (): { [name: string]: string } => {
        const cmd = this.parsedCommand.command;
        const env: { [name: string]: string } = {};
        if (cmd && cmd.env) {
            return cmd.env;
        }
        return env;
    };

    private parseArgsAndOptions = () => {
        this.parseOptions();
        if (this._parsedCommand.command) {
            this.parseArgs();
        }
    };

    public get parsedCommand(): ParsedCliCommand {
        if (!this._parsedCommand) {
            this._parsedCommand = {};
            this._parsedCommand.errors = this._parserErrors;
            this._parsedCommand.program = this._commandPackage;
            this._parsedCommand.run = this.runner;
            this._parsedCommand.version = this.version;
            this.parseCommandLine();
            this.parseArgsAndOptions();
            this._parsedCommand.env = this.getEnv();
        }
        return this._parsedCommand as ParsedCliCommand;
    }

    private getParsedOptionCommandName = () => {
        const parsed = this._parsedCommand;
        return Object.keys(parsed.options)
            .filter(o => typeof parsed.options[o] !== 'undefined')
            .find(o => !!(parsed.optionDefinitions[o] && parsed.optionDefinitions[o].commandHandler));
    };

    private setProcessEnvFromParsedCommand = () => {
        Object.keys(this.parsedCommand.env).forEach(k => {
            process.env[k] = this.parsedCommand.env[k];
        });
    };

    private promptArgsToArgVals = (promptArgs: object): string[] => {
        const cmd = this.parsedCommand.command;
        const defArgs = cmd ? cmd.arguments || [] : [];
        const argVals: string[] = [];

        // Loop through definition arguments, and assign value from promptArgs Hash
        for (let i = 0; i < defArgs.length; i++) {
            const defArg = defArgs[i];
            const promptArgVal = promptArgs[defArg.name];
            if (defArg.isVariadic) {
                const promptArgValAry = Array.isArray(promptArgVal) ? promptArgVal : [promptArgVal];
                argVals.push(...promptArgValAry);
            } else {
                argVals.push(promptArgVal);
            }
        }

        return argVals;
    };

    private runAndParsePrompt = async () => {
        if (this.showPrompts) {
            const parsedCommand = this._parsedCommand as ParsedCliCommand;
            // call out to prompt handler to get args and options
            const promptResult = await this.promptHandler(parsedCommand);
            // reset arg/option errors
            this._parserErrors.clearErrors('argument');
            this._parserErrors.clearErrors('option');
            // convert prompt arg values to command line array to re-parse them
            this._argVals = this.promptArgsToArgVals(promptResult.arguments);
            // assign prompt options to _optionVals to re-parse them
            this._optionVals = promptResult.options;
            // re-parse args and options from prompt values
            this.parseArgsAndOptions();
        }
    };

    private runner = async (): Promise<CliRunResult> => {
        const parsedCommand = this._parsedCommand as ParsedCliCommand;
        // determine if an option is set to call a handler (in to over-ride the command def handler)
        const commandOption = this.getParsedOptionCommandName();
        let exitCode;
        if (commandOption) {
            // a selected option has it's own handler, set it up and run the option's handler (in lieu of the command's handler)
            const commandOptionHandler = parsedCommand.optionDefinitions[commandOption].commandHandler;
            exitCode = await Promise.resolve(commandOptionHandler(parsedCommand));
        } else {
            // delete options that are commands themselves (i.e. '--help', '--version')
            Object.keys(parsedCommand.options)
                .filter(
                    o => !!(parsedCommand.optionDefinitions[o] && parsedCommand.optionDefinitions[o].commandHandler)
                )
                .forEach(o => {
                    delete parsedCommand.options[o];
                });

            await this.runAndParsePrompt();

            if (parsedCommand.errors.hasErrors) {
                // parsed errors, call the errorHandler
                exitCode = (await Promise.resolve(this.errorHandler(parsedCommand))) || 1;
            } else {
                // set process env from command env settings
                this.setProcessEnvFromParsedCommand();

                // call the handler with parsed command
                exitCode = await this.runHandler(parsedCommand);
            }
        }

        return {
            parsedCommand,
            exitCode: typeof exitCode == 'number' ? exitCode : 0,
        };
    };
}