const Manifest = @This();
const std = @import("std");
const mem = std.mem;
const Allocator = std.mem.Allocator;
const assert = std.debug.assert;
const Ast = std.zig.Ast;
const testing = std.testing;
const Package = @import("../Package.zig");

pub const max_bytes = 10 * 1024 * 1024;
pub const basename = "build.zig.zon";
pub const max_name_len = 32;
pub const max_version_len = 32;

pub const Dependency = struct {
    location: Location,
    location_tok: Ast.TokenIndex,
    location_node: Ast.Node.Index,
    hash: ?[]const u8,
    hash_tok: Ast.TokenIndex,
    hash_node: Ast.Node.Index,
    node: Ast.Node.Index,
    name_tok: Ast.TokenIndex,
    lazy: bool,

    pub const Location = union(enum) {
        url: []const u8,
        path: []const u8,
    };
};

pub const ErrorMessage = struct {
    msg: []const u8,
    tok: Ast.TokenIndex,
    off: u32,
};

name: []const u8,
id: u32,
version: std.SemanticVersion,
version_node: Ast.Node.Index,
dependencies: std.StringArrayHashMapUnmanaged(Dependency),
dependencies_node: Ast.Node.Index,
paths: std.StringArrayHashMapUnmanaged(void),
minimum_zig_version: ?std.SemanticVersion,

errors: []ErrorMessage,
arena_state: std.heap.ArenaAllocator.State,

pub const ParseOptions = struct {
    allow_missing_paths_field: bool = false,
    /// Deprecated, to be removed after 0.14.0 is tagged.
    allow_name_string: bool = true,
    /// Deprecated, to be removed after 0.14.0 is tagged.
    allow_missing_fingerprint: bool = true,
};

pub const Error = Allocator.Error;

pub fn parse(gpa: Allocator, ast: Ast, options: ParseOptions) Error!Manifest {
    const node_tags = ast.nodes.items(.tag);
    const node_datas = ast.nodes.items(.data);
    assert(node_tags[0] == .root);
    const main_node_index = node_datas[0].lhs;

    var arena_instance = std.heap.ArenaAllocator.init(gpa);
    errdefer arena_instance.deinit();

    var p: Parse = .{
        .gpa = gpa,
        .ast = ast,
        .arena = arena_instance.allocator(),
        .errors = .{},

        .name = undefined,
        .id = 0,
        .version = undefined,
        .version_node = 0,
        .dependencies = .{},
        .dependencies_node = 0,
        .paths = .{},
        .allow_missing_paths_field = options.allow_missing_paths_field,
        .allow_name_string = options.allow_name_string,
        .allow_missing_fingerprint = options.allow_missing_fingerprint,
        .minimum_zig_version = null,
        .buf = .{},
    };
    defer p.buf.deinit(gpa);
    defer p.errors.deinit(gpa);
    defer p.dependencies.deinit(gpa);
    defer p.paths.deinit(gpa);

    p.parseRoot(main_node_index) catch |err| switch (err) {
        error.ParseFailure => assert(p.errors.items.len > 0),
        else => |e| return e,
    };

    return .{
        .name = p.name,
        .id = p.id,
        .version = p.version,
        .version_node = p.version_node,
        .dependencies = try p.dependencies.clone(p.arena),
        .dependencies_node = p.dependencies_node,
        .paths = try p.paths.clone(p.arena),
        .minimum_zig_version = p.minimum_zig_version,
        .errors = try p.arena.dupe(ErrorMessage, p.errors.items),
        .arena_state = arena_instance.state,
    };
}

pub fn deinit(man: *Manifest, gpa: Allocator) void {
    man.arena_state.promote(gpa).deinit();
    man.* = undefined;
}

pub fn copyErrorsIntoBundle(
    man: Manifest,
    ast: Ast,
    /// ErrorBundle null-terminated string index
    src_path: u32,
    eb: *std.zig.ErrorBundle.Wip,
) Allocator.Error!void {
    const token_starts = ast.tokens.items(.start);

    for (man.errors) |msg| {
        const start_loc = ast.tokenLocation(0, msg.tok);

        try eb.addRootErrorMessage(.{
            .msg = try eb.addString(msg.msg),
            .src_loc = try eb.addSourceLocation(.{
                .src_path = src_path,
                .span_start = token_starts[msg.tok],
                .span_end = @intCast(token_starts[msg.tok] + ast.tokenSlice(msg.tok).len),
                .span_main = token_starts[msg.tok] + msg.off,
                .line = @intCast(start_loc.line),
                .column = @intCast(start_loc.column),
                .source_line = try eb.addString(ast.source[start_loc.line_start..start_loc.line_end]),
            }),
        });
    }
}

const Parse = struct {
    gpa: Allocator,
    ast: Ast,
    arena: Allocator,
    buf: std.ArrayListUnmanaged(u8),
    errors: std.ArrayListUnmanaged(ErrorMessage),

    name: []const u8,
    id: u32,
    version: std.SemanticVersion,
    version_node: Ast.Node.Index,
    dependencies: std.StringArrayHashMapUnmanaged(Dependency),
    dependencies_node: Ast.Node.Index,
    paths: std.StringArrayHashMapUnmanaged(void),
    allow_missing_paths_field: bool,
    allow_name_string: bool,
    allow_missing_fingerprint: bool,
    minimum_zig_version: ?std.SemanticVersion,

    const InnerError = error{ ParseFailure, OutOfMemory };

    fn parseRoot(p: *Parse, node: Ast.Node.Index) !void {
        const ast = p.ast;
        const main_tokens = ast.nodes.items(.main_token);
        const main_token = main_tokens[node];

        var buf: [2]Ast.Node.Index = undefined;
        const struct_init = ast.fullStructInit(&buf, node) orelse {
            return fail(p, main_token, "expected top level expression to be a struct", .{});
        };

        var have_name = false;
        var have_version = false;
        var have_included_paths = false;
        var fingerprint: ?Package.Fingerprint = null;

        for (struct_init.ast.fields) |field_init| {
            const name_token = ast.firstToken(field_init) - 2;
            const field_name = try identifierTokenString(p, name_token);
            // We could get fancy with reflection and comptime logic here but doing
            // things manually provides an opportunity to do any additional verification
            // that is desirable on a per-field basis.
            if (mem.eql(u8, field_name, "dependencies")) {
                p.dependencies_node = field_init;
                try parseDependencies(p, field_init);
            } else if (mem.eql(u8, field_name, "paths")) {
                have_included_paths = true;
                try parseIncludedPaths(p, field_init);
            } else if (mem.eql(u8, field_name, "name")) {
                p.name = try parseName(p, field_init);
                have_name = true;
            } else if (mem.eql(u8, field_name, "fingerprint")) {
                fingerprint = try parseFingerprint(p, field_init);
            } else if (mem.eql(u8, field_name, "version")) {
                p.version_node = field_init;
                const version_text = try parseString(p, field_init);
                if (version_text.len > max_version_len) {
                    try appendError(p, main_tokens[field_init], "version string length {d} exceeds maximum of {d}", .{ version_text.len, max_version_len });
                }
                p.version = std.SemanticVersion.parse(version_text) catch |err| v: {
                    try appendError(p, main_tokens[field_init], "unable to parse semantic version: {s}", .{@errorName(err)});
                    break :v undefined;
                };
                have_version = true;
            } else if (mem.eql(u8, field_name, "minimum_zig_version")) {
                const version_text = try parseString(p, field_init);
                p.minimum_zig_version = std.SemanticVersion.parse(version_text) catch |err| v: {
                    try appendError(p, main_tokens[field_init], "unable to parse semantic version: {s}", .{@errorName(err)});
                    break :v null;
                };
            } else {
                // Ignore unknown fields so that we can add fields in future zig
                // versions without breaking older zig versions.
            }
        }

        if (!have_name) {
            try appendError(p, main_token, "missing top-level 'name' field", .{});
        } else {
            if (fingerprint) |n| {
                if (!n.validate(p.name)) {
                    return fail(p, main_token, "invalid fingerprint: 0x{x}; if this is a new or forked package, use this value: 0x{x}", .{
                        n.int(), Package.Fingerprint.generate(p.name).int(),
                    });
                }
                p.id = n.id;
            } else if (!p.allow_missing_fingerprint) {
                try appendError(p, main_token, "missing top-level 'fingerprint' field; suggested value: 0x{x}", .{
                    Package.Fingerprint.generate(p.name).int(),
                });
            } else {
                p.id = 0;
            }
        }

        if (!have_version) {
            try appendError(p, main_token, "missing top-level 'version' field", .{});
        }

        if (!have_included_paths) {
            if (p.allow_missing_paths_field) {
                try p.paths.put(p.gpa, "", {});
            } else {
                try appendError(p, main_token, "missing top-level 'paths' field", .{});
            }
        }
    }

    fn parseDependencies(p: *Parse, node: Ast.Node.Index) !void {
        const ast = p.ast;
        const main_tokens = ast.nodes.items(.main_token);

        var buf: [2]Ast.Node.Index = undefined;
        const struct_init = ast.fullStructInit(&buf, node) orelse {
            const tok = main_tokens[node];
            return fail(p, tok, "expected dependencies expression to be a struct", .{});
        };

        for (struct_init.ast.fields) |field_init| {
            const name_token = ast.firstToken(field_init) - 2;
            const dep_name = try identifierTokenString(p, name_token);
            const dep = try parseDependency(p, field_init);
            try p.dependencies.put(p.gpa, dep_name, dep);
        }
    }

    fn parseDependency(p: *Parse, node: Ast.Node.Index) !Dependency {
        const ast = p.ast;
        const main_tokens = ast.nodes.items(.main_token);

        var buf: [2]Ast.Node.Index = undefined;
        const struct_init = ast.fullStructInit(&buf, node) orelse {
            const tok = main_tokens[node];
            return fail(p, tok, "expected dependency expression to be a struct", .{});
        };

        var dep: Dependency = .{
            .location = undefined,
            .location_tok = 0,
            .location_node = undefined,
            .hash = null,
            .hash_tok = 0,
            .hash_node = undefined,
            .node = node,
            .name_tok = 0,
            .lazy = false,
        };
        var has_location = false;

        for (struct_init.ast.fields) |field_init| {
            const name_token = ast.firstToken(field_init) - 2;
            dep.name_tok = name_token;
            const field_name = try identifierTokenString(p, name_token);
            // We could get fancy with reflection and comptime logic here but doing
            // things manually provides an opportunity to do any additional verification
            // that is desirable on a per-field basis.
            if (mem.eql(u8, field_name, "url")) {
                if (has_location) {
                    return fail(p, main_tokens[field_init], "dependency should specify only one of 'url' and 'path' fields.", .{});
                }
                dep.location = .{
                    .url = parseString(p, field_init) catch |err| switch (err) {
                        error.ParseFailure => continue,
                        else => |e| return e,
                    },
                };
                has_location = true;
                dep.location_tok = main_tokens[field_init];
                dep.location_node = field_init;
            } else if (mem.eql(u8, field_name, "path")) {
                if (has_location) {
                    return fail(p, main_tokens[field_init], "dependency should specify only one of 'url' and 'path' fields.", .{});
                }
                dep.location = .{
                    .path = parseString(p, field_init) catch |err| switch (err) {
                        error.ParseFailure => continue,
                        else => |e| return e,
                    },
                };
                has_location = true;
                dep.location_tok = main_tokens[field_init];
                dep.location_node = field_init;
            } else if (mem.eql(u8, field_name, "hash")) {
                dep.hash = parseHash(p, field_init) catch |err| switch (err) {
                    error.ParseFailure => continue,
                    else => |e| return e,
                };
                dep.hash_tok = main_tokens[field_init];
                dep.hash_node = field_init;
            } else if (mem.eql(u8, field_name, "lazy")) {
                dep.lazy = parseBool(p, field_init) catch |err| switch (err) {
                    error.ParseFailure => continue,
                    else => |e| return e,
                };
            } else {
                // Ignore unknown fields so that we can add fields in future zig
                // versions without breaking older zig versions.
            }
        }

        if (!has_location) {
            try appendError(p, main_tokens[node], "dependency requires location field, one of 'url' or 'path'.", .{});
        }

        return dep;
    }

    fn parseIncludedPaths(p: *Parse, node: Ast.Node.Index) !void {
        const ast = p.ast;
        const main_tokens = ast.nodes.items(.main_token);

        var buf: [2]Ast.Node.Index = undefined;
        const array_init = ast.fullArrayInit(&buf, node) orelse {
            const tok = main_tokens[node];
            return fail(p, tok, "expected paths expression to be a list of strings", .{});
        };

        for (array_init.ast.elements) |elem_node| {
            const path_string = try parseString(p, elem_node);
            // This is normalized so that it can be used in string comparisons
            // against file system paths.
            const normalized = try std.fs.path.resolve(p.arena, &.{path_string});
            try p.paths.put(p.gpa, normalized, {});
        }
    }

    fn parseBool(p: *Parse, node: Ast.Node.Index) !bool {
        const ast = p.ast;
        const node_tags = ast.nodes.items(.tag);
        const main_tokens = ast.nodes.items(.main_token);
        if (node_tags[node] != .identifier) {
            return fail(p, main_tokens[node], "expected identifier", .{});
        }
        const ident_token = main_tokens[node];
        const token_bytes = ast.tokenSlice(ident_token);
        if (mem.eql(u8, token_bytes, "true")) {
            return true;
        } else if (mem.eql(u8, token_bytes, "false")) {
            return false;
        } else {
            return fail(p, ident_token, "expected boolean", .{});
        }
    }

    fn parseFingerprint(p: *Parse, node: Ast.Node.Index) !Package.Fingerprint {
        const ast = p.ast;
        const node_tags = ast.nodes.items(.tag);
        const main_tokens = ast.nodes.items(.main_token);
        const main_token = main_tokens[node];
        if (node_tags[node] != .number_literal) {
            return fail(p, main_token, "expected integer literal", .{});
        }
        const token_bytes = ast.tokenSlice(main_token);
        const parsed = std.zig.parseNumberLiteral(token_bytes);
        switch (parsed) {
            .int => |n| return @bitCast(n),
            .big_int, .float => return fail(p, main_token, "expected u64 integer literal, found {s}", .{
                @tagName(parsed),
            }),
            .failure => |err| return fail(p, main_token, "bad integer literal: {s}", .{@tagName(err)}),
        }
    }

    fn parseName(p: *Parse, node: Ast.Node.Index) ![]const u8 {
        const ast = p.ast;
        const node_tags = ast.nodes.items(.tag);
        const main_tokens = ast.nodes.items(.main_token);
        const main_token = main_tokens[node];

        if (p.allow_name_string and node_tags[node] == .string_literal) {
            const name = try parseString(p, node);
            if (!std.zig.isValidId(name))
                return fail(p, main_token, "name must be a valid bare zig identifier (hint: switch from string to enum literal)", .{});

            if (name.len > max_name_len)
                return fail(p, main_token, "name '{}' exceeds max length of {d}", .{
                    std.zig.fmtId(name), max_name_len,
                });

            return name;
        }

        if (node_tags[node] != .enum_literal)
            return fail(p, main_token, "expected enum literal", .{});

        const ident_name = ast.tokenSlice(main_token);
        if (mem.startsWith(u8, ident_name, "@"))
            return fail(p, main_token, "name must be a valid bare zig identifier", .{});

        if (ident_name.len > max_name_len)
            return fail(p, main_token, "name '{}' exceeds max length of {d}", .{
                std.zig.fmtId(ident_name), max_name_len,
            });

        return ident_name;
    }

    fn parseString(p: *Parse, node: Ast.Node.Index) ![]const u8 {
        const ast = p.ast;
        const node_tags = ast.nodes.items(.tag);
        const main_tokens = ast.nodes.items(.main_token);
        if (node_tags[node] != .string_literal) {
            return fail(p, main_tokens[node], "expected string literal", .{});
        }
        const str_lit_token = main_tokens[node];
        const token_bytes = ast.tokenSlice(str_lit_token);
        p.buf.clearRetainingCapacity();
        try parseStrLit(p, str_lit_token, &p.buf, token_bytes, 0);
        const duped = try p.arena.dupe(u8, p.buf.items);
        return duped;
    }

    fn parseHash(p: *Parse, node: Ast.Node.Index) ![]const u8 {
        const ast = p.ast;
        const main_tokens = ast.nodes.items(.main_token);
        const tok = main_tokens[node];
        const h = try parseString(p, node);

        if (h.len > Package.Hash.max_len) {
            return fail(p, tok, "hash length exceeds maximum: {d}", .{h.len});
        }

        return h;
    }

    /// TODO: try to DRY this with AstGen.identifierTokenString
    fn identifierTokenString(p: *Parse, token: Ast.TokenIndex) InnerError![]const u8 {
        const ast = p.ast;
        const token_tags = ast.tokens.items(.tag);
        assert(token_tags[token] == .identifier);
        const ident_name = ast.tokenSlice(token);
        if (!mem.startsWith(u8, ident_name, "@")) {
            return ident_name;
        }
        p.buf.clearRetainingCapacity();
        try parseStrLit(p, token, &p.buf, ident_name, 1);
        const duped = try p.arena.dupe(u8, p.buf.items);
        return duped;
    }

    /// TODO: try to DRY this with AstGen.parseStrLit
    fn parseStrLit(
        p: *Parse,
        token: Ast.TokenIndex,
        buf: *std.ArrayListUnmanaged(u8),
        bytes: []const u8,
        offset: u32,
    ) InnerError!void {
        const raw_string = bytes[offset..];
        var buf_managed = buf.toManaged(p.gpa);
        const result = std.zig.string_literal.parseWrite(buf_managed.writer(), raw_string);
        buf.* = buf_managed.moveToUnmanaged();
        switch (try result) {
            .success => {},
            .failure => |err| try p.appendStrLitError(err, token, bytes, offset),
        }
    }

    /// TODO: try to DRY this with AstGen.failWithStrLitError
    fn appendStrLitError(
        p: *Parse,
        err: std.zig.string_literal.Error,
        token: Ast.TokenIndex,
        bytes: []const u8,
        offset: u32,
    ) Allocator.Error!void {
        const raw_string = bytes[offset..];
        switch (err) {
            .invalid_escape_character => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "invalid escape character: '{c}'",
                    .{raw_string[bad_index]},
                );
            },
            .expected_hex_digit => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "expected hex digit, found '{c}'",
                    .{raw_string[bad_index]},
                );
            },
            .empty_unicode_escape_sequence => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "empty unicode escape sequence",
                    .{},
                );
            },
            .expected_hex_digit_or_rbrace => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "expected hex digit or '}}', found '{c}'",
                    .{raw_string[bad_index]},
                );
            },
            .invalid_unicode_codepoint => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "unicode escape does not correspond to a valid unicode scalar value",
                    .{},
                );
            },
            .expected_lbrace => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "expected '{{', found '{c}",
                    .{raw_string[bad_index]},
                );
            },
            .expected_rbrace => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "expected '}}', found '{c}",
                    .{raw_string[bad_index]},
                );
            },
            .expected_single_quote => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "expected single quote ('), found '{c}",
                    .{raw_string[bad_index]},
                );
            },
            .invalid_character => |bad_index| {
                try p.appendErrorOff(
                    token,
                    offset + @as(u32, @intCast(bad_index)),
                    "invalid byte in string or character literal: '{c}'",
                    .{raw_string[bad_index]},
                );
            },
            .empty_char_literal => {
                try p.appendErrorOff(token, offset, "empty character literal", .{});
            },
        }
    }

    fn fail(
        p: *Parse,
        tok: Ast.TokenIndex,
        comptime fmt: []const u8,
        args: anytype,
    ) InnerError {
        try appendError(p, tok, fmt, args);
        return error.ParseFailure;
    }

    fn appendError(p: *Parse, tok: Ast.TokenIndex, comptime fmt: []const u8, args: anytype) !void {
        return appendErrorOff(p, tok, 0, fmt, args);
    }

    fn appendErrorOff(
        p: *Parse,
        tok: Ast.TokenIndex,
        byte_offset: u32,
        comptime fmt: []const u8,
        args: anytype,
    ) Allocator.Error!void {
        try p.errors.append(p.gpa, .{
            .msg = try std.fmt.allocPrint(p.arena, fmt, args),
            .tok = tok,
            .off = byte_offset,
        });
    }
};

test "basic" {
    const gpa = testing.allocator;

    const example =
        \\.{
        \\    .name = "foo",
        \\    .version = "3.2.1",
        \\    .paths = .{""},
        \\    .dependencies = .{
        \\        .bar = .{
        \\            .url = "https://example.com/baz.tar.gz",
        \\            .hash = "1220f1b680b6065fcfc94fe777f22e73bcb7e2767e5f4d99d4255fe76ded69c7a35f",
        \\        },
        \\    },
        \\}
    ;

    var ast = try Ast.parse(gpa, example, .zon);
    defer ast.deinit(gpa);

    try testing.expect(ast.errors.len == 0);

    var manifest = try Manifest.parse(gpa, ast, .{});
    defer manifest.deinit(gpa);

    try testing.expect(manifest.errors.len == 0);
    try testing.expectEqualStrings("foo", manifest.name);

    try testing.expectEqual(@as(std.SemanticVersion, .{
        .major = 3,
        .minor = 2,
        .patch = 1,
    }), manifest.version);

    try testing.expect(manifest.dependencies.count() == 1);
    try testing.expectEqualStrings("bar", manifest.dependencies.keys()[0]);
    try testing.expectEqualStrings(
        "https://example.com/baz.tar.gz",
        manifest.dependencies.values()[0].location.url,
    );
    try testing.expectEqualStrings(
        "1220f1b680b6065fcfc94fe777f22e73bcb7e2767e5f4d99d4255fe76ded69c7a35f",
        manifest.dependencies.values()[0].hash orelse return error.TestFailed,
    );

    try testing.expect(manifest.minimum_zig_version == null);
}

test "minimum_zig_version" {
    const gpa = testing.allocator;

    const example =
        \\.{
        \\    .name = "foo",
        \\    .version = "3.2.1",
        \\    .paths = .{""},
        \\    .minimum_zig_version = "0.11.1",
        \\}
    ;

    var ast = try Ast.parse(gpa, example, .zon);
    defer ast.deinit(gpa);

    try testing.expect(ast.errors.len == 0);

    var manifest = try Manifest.parse(gpa, ast, .{});
    defer manifest.deinit(gpa);

    try testing.expect(manifest.errors.len == 0);
    try testing.expect(manifest.dependencies.count() == 0);

    try testing.expect(manifest.minimum_zig_version != null);

    try testing.expectEqual(@as(std.SemanticVersion, .{
        .major = 0,
        .minor = 11,
        .patch = 1,
    }), manifest.minimum_zig_version.?);
}

test "minimum_zig_version - invalid version" {
    const gpa = testing.allocator;

    const example =
        \\.{
        \\    .name = "foo",
        \\    .version = "3.2.1",
        \\    .minimum_zig_version = "X.11.1",
        \\    .paths = .{""},
        \\}
    ;

    var ast = try Ast.parse(gpa, example, .zon);
    defer ast.deinit(gpa);

    try testing.expect(ast.errors.len == 0);

    var manifest = try Manifest.parse(gpa, ast, .{});
    defer manifest.deinit(gpa);

    try testing.expect(manifest.errors.len == 1);
    try testing.expect(manifest.dependencies.count() == 0);

    try testing.expect(manifest.minimum_zig_version == null);
}