import { tokenize } from './lexer'
import { Parser } from './parser'
import { compile, recompile, definitions, freeVars, dependencies, dependents, astRegistry } from './compiler'
import { prettyPrint } from './ast'
import type { AST } from './ast'
import { measure } from './ui';

const STORAGE_KEY = 'cg-definitions';

export const store: Record<string, any> = {};

export const _rt = {
    add: (a: number) => (b: number) => a + b,
    sub: (a: number) => (b: number) => a - b,
    mul: (a: number) => (b: number) => a * b,
    div: (a: number) => (b: number) => a / b,
    mod: (a: number) => (b: number) => a % b,
    pow: (a: number) => (b: number) => a ** b,
    cat: (a: any) => (b: any) => Array.isArray(a) ? [...a, ...b] : a + b,
    max: (a: number) => (b: number) => Math.max(a, b),
    min: (a: number) => (b: number) => Math.min(a, b),

    eq: (a: any) => (b: any) => ({ _tag: deepEqual(a, b) ? 'True' : 'False' }),
    neq: (a: any) => (b: any) => ({ _tag: deepEqual(a, b) ? 'False' : 'True' }),
    gt: (a: any) => (b: any) => ({ _tag: a > b ? 'True' : 'False' }),
    lt: (a: any) => (b: any) => ({ _tag: a < b ? 'True' : 'False' }),
    gte: (a: any) => (b: any) => ({ _tag: a >= b ? 'True' : 'False' }),
    lte: (a: any) => (b: any) => ({ _tag: a <= b ? 'True' : 'False' }),

    ui: {
        rect: (config: any) => ({ kind: 'rect', ...config }),
        text: (config: any) => ({ kind: 'text', ...config }),
        stack: (config: any) => ({ kind: 'stack', ...config }),
        row: (config: any) => ({ kind: 'row', ...config }),
        column: (config: any) => ({ kind: 'column', ...config }),
        padding: (config: any) => ({ kind: 'padding', ...config }),
        positioned: (config: any) => ({ kind: 'positioned', ...config }),
        clickable: (config: any) => ({ kind: 'clickable', ...config }),
        clip: (config: any) => ({ kind: 'clip', ...config }),
        opacity: (config: any) => ({ kind: 'opacity', ...config }),
        stateful: (config: any) => ({ kind: 'stateful', ...config }),
        measure: (config: any) => ({ kind: 'measure', ...config }),
        measureText: (text: string) => {
            const canvas = document.createElement('canvas');
            const ctx = canvas.getContext('2d');
            if (ctx) {
                ctx.font = '16px "SF Mono", "Monaco", "Menlo", monospace';
                return Math.floor(ctx.measureText(text).width);
            }
            return text.length * 10; // fallback
        },
    },

    measure: measure,

    batch: (events: any[]) => ({ _tag: 'Batch', _0: events }),
    noOp: { _tag: 'NoOp' },
    focus: (key: string) => ({ _tag: 'Focus', _0: key }),

    nth: (i: number) => (xs: any[] | string) => i >= 0 && i < xs.length
        ? { _tag: 'Some', _0: xs[i] }
        : { _tag: 'None' },
    len: (xs: any[] | string) => xs.length,
    // str: (x: any) => String(x),
    show: (value: any): string => {
        if (value === null || value === undefined) return "None";
        if (typeof value === 'string') return value;
        if (typeof value === 'number') return String(value);
        if (typeof value === 'boolean') return value ? "True" : "False";
        if (value._tag) return value._0 !== undefined ? `${value._tag} ${_rt.show(value._0)}` : value._tag;
        if (Array.isArray(value)) return `[${value.map(_rt.show).join(", ")}]`;
        if (typeof value === 'function') return "<function>";
        if (typeof value === 'object') {
            const entries = Object.entries(value).map(([k, v]) => `${k} = ${_rt.show(v)}`);
            return `{ ${entries.join(", ")} }`;
        }
        return String(value);
    },
    chars: (s: string) => s.split(''),
    join: (delim: string) => (xs: string[]) => xs.join(delim),
    split: (delim: string) => (xs: string) => xs.split(delim),
    slice: (s: string | any[]) => (start: number) => (end: number) => s.slice(start, end),
    debug: (label: string) => (value: any) => { console.log(label, value); return value; },
    fuzzyMatch: (query: string) => (target: string) => {
        const q = query.toLowerCase();
        const t = target.toLowerCase();
        let qi = 0;
        for (let ti = 0; ti < t.length && qi < q.length; ti++) {
            if (t[ti] === q[qi]) qi++;
        }
        return { _tag: qi === q.length ? 'True' : 'False' };
    },
    storeSearch: (query: string) => {
        return Object.keys(store).filter(name => _rt.fuzzyMatch(query)(name)._tag === 'True');
    },
    getSource: (name: string) => {
        const ast = definitions.get(name);
        if (!ast) return "";
        const printed = prettyPrint(ast);
        return printed;
    },
    rebind: (name: string, pathOrValue: any, maybeValue?: any) => {
        if (maybeValue === undefined) {
            store[name] = pathOrValue;
        } else {
            const path = pathOrValue as string[];
            let obj = store[name];
            for (let i = 0; i < path.length - 1; i++) {
                obj = obj[path[i]];
            }
            obj[path[path.length - 1]] = maybeValue;
        }
        syncToAst(name);
    },
    redefine: (name: string) => (code: string) => {
        const tokens = tokenize(`_tmp = ${code};`);
        const parser = new Parser(tokens, "");
        const defs = parser.parse();
        recompile(name, defs[0]. body);
        return { _tag: 'Ok' };
    },
    undefine: (name: string) => {
        delete store[name];
        definitions.delete(name);
        dependencies.delete(name);
        dependents.delete(name);
        saveDefinitions();
        return { _tag: 'Ok' };
    },

    eval: (code: string) => {
        const trimmed = code.trim();

        // is it a definition
        const defMatch = /^([a-z_][a-zA-Z0-9_]*)\s*=(?![=])/.exec(trimmed);

        if (defMatch) {
            try {
                const fullCode = trimmed.endsWith(';') ? trimmed : trimmed + ';';
                const tokens = tokenize(fullCode);
                const parser = new Parser(tokens, fullCode);
                const defs = parser.parse();

                if (defs.length > 0) {
                    const def = defs[0];
                    recompile(def.name, def.body);
                    saveDefinitions();
                    return { _tag: 'Defined', _0: def.name };
                }
            } catch (e: any) {
                return { _tag: 'Err', _0: e.message };
            }
        }

        // its an expression
        try {
            const wrapped = `_expr = ${trimmed};`;
            const tokens = tokenize(wrapped);
            const parser = new Parser(tokens, wrapped);
            const defs = parser.parse();
            const ast = defs[0].body;

            // validate free vars
            const free = freeVars(ast);
            const allowed = new Set([
                ...Object.keys(store),
                ...Object.keys(_rt)
            ]);
            const unknown = [...free].filter(v => !allowed.has(v));
            if (unknown.length > 0) {
                return { _tag: 'Err', _0: `Unknown: ${unknown.join(', ')}` };
            }

            const compiled = compile(defs[0].body);
            const fn = new Function('_rt', 'store', `return ${compiled}`);
            const result = fn(_rt, store);
            return { _tag: 'Value', _0: result };
        } catch (e: any) {
            return { _tag: 'Err', _0: e.message };
        }
    }
}

export function saveDefinitions() {
    const saved: Record<string, string> = {};
    for (const [name, ast] of definitions) {
        const source = prettyPrint({ kind: 'definition', name, body: ast });
        saved[name] = source;
    }
    localStorage.setItem(STORAGE_KEY, JSON.stringify(saved));

}

export function loadDefinitions() {
    const data = localStorage.getItem(STORAGE_KEY);
    if (!data) return;

    try {
        const saved = JSON.parse(data);
        for (const [_, source] of Object.entries(saved)) {
            const tokens = tokenize(source as string);
            const parser = new Parser(tokens, source as string);
            const defs = parser.parse();
            if (defs.length > 0) {
                recompile(defs[0].name, defs[0].body);
            }
        }
    } catch (e) {
        console.error('Failed to load definitions:', e);
        console.log(data);
    }
}

function valueToAst(value: any): AST {
    // Numbers
    if (typeof value === 'number') {
        return {
            kind: 'literal',
            value: Number.isInteger(value)
            ? { kind: 'int', value }
            : { kind: 'float', value}
        };
    }

    // Strings
    if (typeof value === 'string') {
        return { kind: 'literal', value: { kind: 'string', value } };
    }

    // Arrays
    if (Array.isArray(value)) {
        return { kind: 'list', elements: value.map(valueToAst) };
    }

    // Constructor
    if (typeof value === 'object' && value !== null && value._tag) {
        const tag = value._tag;

        if ('_0' in value) {
            return {
                kind: 'apply',
                func: { kind: 'constructor', name: tag },
                args: [valueToAst(value._0)]
            };
        }

        return { kind: 'constructor', name: tag };
    }

    // Records
    if (typeof value === 'object' && value !== null && !value._tag) {
        const entries = Object.entries(value).map(([k, v]) => ({
            kind: 'field' as const,
            key: k,
            value: valueToAst(v)
        }));
        return { kind: 'record', entries };
    }

    // Functions
    if (typeof value === 'function') {
        if (value._astId !== undefined) {
            return astRegistry.get(value._astId)!;
        }

        throw new Error('Cannot serialize function without _astId');
    }

    throw new Error(`Cannot convert to AST: ${typeof value}`);
}

export function syncToAst(name: string) {
    if (definitions.has(name)) {
        definitions.set(name, valueToAst(store[name]));
        saveDefinitions();
    }
}

function deepEqual(a: any, b: any): boolean {
    if (a === b) return true;
    if (a === null || b === null || typeof a !== 'object' || typeof b !== 'object') return false;
    if (Array.isArray(a) !== Array.isArray(b)) return false;
    if (Array.isArray(a)) {
        if (a.length !== b.length) return false;
        return a.every((v, i) => deepEqual(v, b[i]));
    }
    const keysA = Object.keys(a);
    const keysB = Object.keys(b);
    if (keysA.length !== keysB.length) return false;
    return keysA.every(k => deepEqual(a[k], b[k]));
}