import {
    addIssue,
    BaseSchema,
    type INVALID,
} from "../../core/schema/schema.js";
import type { ParseContext } from "../../types/common.js";

// ---------------------------------------------------------------------------
// Constraints stored on the schema
// ---------------------------------------------------------------------------

interface StringConstraints {
    min?: number;
    max?: number;
    length?: number;
    regex?: RegExp;
    email?: boolean;
    url?: boolean;
    uuid?: boolean;
    startsWith?: string;
    endsWith?: string;
    includes?: string;
    trim?: boolean;
    toLowerCase?: boolean;
    toUpperCase?: boolean;
}

const UUID_RE =
    /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

// ---------------------------------------------------------------------------
// StringSchema
// ---------------------------------------------------------------------------

export class StringSchema extends BaseSchema<string, string> {
    private readonly _constraints: StringConstraints;

    constructor(constraints: StringConstraints = {}) {
        super();
        this._constraints = constraints;
    }

    _parse(input: unknown, ctx: ParseContext): string | INVALID {
        if (typeof input !== "string") {
            return addIssue(ctx, {
                code: "VALIDATION.INVALID_TYPE",
                path: [...ctx.path],
                message: `Expected string, received ${typeof input}`,
                input,
            });
        }

        let value = input;
        const c = this._constraints;

        // Transforms (applied before constraint checks)
        if (c.trim) value = value.trim();
        if (c.toLowerCase) value = value.toLowerCase();
        if (c.toUpperCase) value = value.toUpperCase();

        // Constraints
        if (c.min !== undefined && value.length < c.min) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.TOO_SHORT",
                path: [...ctx.path],
                message: `String must be at least ${c.min} character(s)`,
                input,
            });
        }
        if (c.max !== undefined && value.length > c.max) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.TOO_LONG",
                path: [...ctx.path],
                message: `String must be at most ${c.max} character(s)`,
                input,
            });
        }
        if (c.length !== undefined && value.length !== c.length) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: `String must be exactly ${c.length} character(s)`,
                input,
            });
        }
        if (c.regex !== undefined && !c.regex.test(value)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: `String does not match pattern ${c.regex.toString()}`,
                input,
            });
        }
        if (c.email && !EMAIL_RE.test(value)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: "Invalid email address",
                input,
            });
        }
        if (
            c.url &&
            !value.startsWith("http://") &&
            !value.startsWith("https://")
        ) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: "Invalid URL",
                input,
            });
        }
        if (c.uuid && !UUID_RE.test(value)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: "Invalid UUID",
                input,
            });
        }
        if (c.startsWith !== undefined && !value.startsWith(c.startsWith)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: `String must start with "${c.startsWith}"`,
                input,
            });
        }
        if (c.endsWith !== undefined && !value.endsWith(c.endsWith)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: `String must end with "${c.endsWith}"`,
                input,
            });
        }
        if (c.includes !== undefined && !value.includes(c.includes)) {
            return addIssue(ctx, {
                code: "VALIDATION.STRING.INVALID_FORMAT",
                path: [...ctx.path],
                message: `String must include "${c.includes}"`,
                input,
            });
        }

        return value;
    }

    // -------------------------------------------------------------------------
    // Constraint builders (return new instance for immutability)
    // -------------------------------------------------------------------------

    min(n: number): StringSchema {
        return new StringSchema({ ...this._constraints, min: n });
    }

    max(n: number): StringSchema {
        return new StringSchema({ ...this._constraints, max: n });
    }

    length(n: number): StringSchema {
        return new StringSchema({ ...this._constraints, length: n });
    }

    regex(re: RegExp): StringSchema {
        return new StringSchema({ ...this._constraints, regex: re });
    }

    email(): StringSchema {
        return new StringSchema({ ...this._constraints, email: true });
    }

    url(): StringSchema {
        return new StringSchema({ ...this._constraints, url: true });
    }

    uuid(): StringSchema {
        return new StringSchema({ ...this._constraints, uuid: true });
    }

    startsWith(prefix: string): StringSchema {
        return new StringSchema({ ...this._constraints, startsWith: prefix });
    }

    endsWith(suffix: string): StringSchema {
        return new StringSchema({ ...this._constraints, endsWith: suffix });
    }

    includes(substr: string): StringSchema {
        return new StringSchema({ ...this._constraints, includes: substr });
    }

    trim(): StringSchema {
        return new StringSchema({ ...this._constraints, trim: true });
    }

    toLowerCase(): StringSchema {
        return new StringSchema({ ...this._constraints, toLowerCase: true });
    }

    toUpperCase(): StringSchema {
        return new StringSchema({ ...this._constraints, toUpperCase: true });
    }
}

// ---------------------------------------------------------------------------
// Factory
// ---------------------------------------------------------------------------

export function string(): StringSchema {
    return new StringSchema();
}