const std = @import("std");

const Allocator = std.mem.Allocator;
const ArrayListUnmanaged = std.ArrayListUnmanaged;

const Context = @import("context.zig").Context;
const Value = @import("context.zig").Value;

const builtin_filters = @import("filters.zig").builtin_filters;
const FilterError = @import("filters.zig").FilterError;
const parser = @import("parser.zig");
const TemplateCache = @import("cache.zig").TemplateCache;

pub const RenderError = error{
    InvalidCharacter,
    InvalidSyntax,
    OutOfMemory,
    Overflow,
    Unexpected,
    UnsupportedExpression,
} || FilterError || parser.ParserError || std.fs.File.OpenError;

pub const Renderer = struct {
    context: *Context,
    allocator: Allocator,
    cache: *TemplateCache,

    pub fn init(context: *Context, cache: *TemplateCache) Renderer {
        return .{
            .context = context,
            .allocator = context.allocator(),
            .cache = cache,
        };
    }

    fn checkForExtends(self: *const Renderer, nodes: []parser.Node) ?parser.Node {
        _ = self;
        for (nodes) |n| {
            if (n.type == .extends) return n;
        }
        return null;
    }

    fn readTemplateFile(self: *const Renderer, path: []const u8) ![]const u8 {
        const max_size = 10 * 1024 * 1024;

        const full_path = try std.fs.path.join(self.allocator, &.{ self.cache.default_path.?, path });
        defer self.allocator.free(full_path);

        const file = try std.fs.cwd().openFile(full_path, .{});
        defer file.close();

        // return std.fs.cwd().readFileAlloc(self.allocator, path, max_size) catch |err| switch (err) {
        return file.readToEndAlloc(self.allocator, max_size) catch |err| switch (err) {
            else => return RenderError.Unexpected,
        };
    }

    fn renderNodes(self: *const Renderer, alloc: Allocator, nodes: []parser.Node, writer: anytype) RenderError!void {
        const extends_node = self.checkForExtends(nodes);

        if (extends_node) |ext| {
            const base_template = try self.readTemplateFile(ext.extends.?.parent_name);
            defer self.allocator.free(base_template);

            var base_parser = parser.Parser.init(base_template);
            const base_nodes = try base_parser.parse(alloc);
            defer {
                for (base_nodes) |n| n.deinit(alloc);
                alloc.free(base_nodes);
            }
            try self.renderWithInheritance(alloc, base_nodes, nodes, writer);
        } else {
            for (nodes) |node| {
                try self.renderNode(alloc, nodes, node, writer, null, null);
            }
        }
    }

    fn renderTemplate(self: *const Renderer, template: []const u8, writer: anytype, cache_key: ?[]const u8) RenderError!void {
        var arena = std.heap.ArenaAllocator.init(self.allocator);
        defer arena.deinit();
        const alloc = arena.allocator();

        if (cache_key) |ck| {
            if (self.cache.get(ck)) |cached_nodes| {
                try self.renderNodes(alloc, cached_nodes, writer);
                return;
            }
        }

        var p = parser.Parser.init(template);
        const nodes = try p.parse(alloc);
        defer {
            for (nodes) |node| node.deinit(alloc);
            alloc.free(nodes);
        }

        if (cache_key) |ck| {
            var alc = self.cache.allocator();
            var cached_nodes = try alc.alloc(parser.Node, nodes.len);
            errdefer alc.free(cached_nodes);
            for (nodes, 0..) |node, i| {
                cached_nodes[i] = try node.clone(self.allocator);
                std.debug.print("clonou {any}\n", .{cached_nodes[i]});
            }
            try self.cache.add(ck, nodes);
        }

        return try self.renderNodes(alloc, nodes, writer);
    }

    pub fn render(self: *const Renderer, template_path: []const u8, writer: anytype) RenderError!void {
        const base_template = try self.readTemplateFile(template_path);
        defer self.allocator.free(base_template);

        return try self.renderTemplate(base_template, writer, template_path);
    }

    pub fn renderString(self: *const Renderer, template: []const u8, writer: anytype) RenderError!void {
        return try self.renderTemplate(template, writer, null);
    }

    fn renderWithInheritance(self: *const Renderer, alloc: Allocator, base_nodes: []parser.Node, child_nodes: []parser.Node, writer: anytype) RenderError!void {
        for (base_nodes) |base_node| {
            if (base_node.type == .block) {
                const block_name = base_node.block.?.name;

                // Procura no filho
                const child_block = self.findChildBlock(child_nodes, block_name);
                if (child_block) |child| {
                    // Renderiza o filho, passando o conteúdo do pai para block.super
                    for (child.body) |child_node| {
                        try self.renderNode(alloc, child_nodes, child_node, writer, null, base_node.block.?.body);
                    }
                } else {
                    // Renderiza o do pai
                    for (base_node.block.?.body) |child| {
                        try self.renderNode(alloc, child_nodes, child, writer, null, null);
                    }
                }
            } else {
                // Qualquer outra coisa no base
                try self.renderNode(alloc, child_nodes, base_node, writer, null, null);
            }
        }
    }

    fn renderNode(self: *const Renderer, alloc: Allocator, nodes: []parser.Node, node: parser.Node, writer: anytype, context: ?*Context, parent_block_nodes: ?[]parser.Node) RenderError!void {
        switch (node.type) {
            .text => try writer.writeAll(node.text.?.content),
            .variable => {
                const var_name = node.variable.?.expr;
                var value: Value = Value.null;
                if (context != null) {
                    value = context.?.get(var_name) orelse Value.null;
                } else {
                    value = self.context.get(var_name) orelse Value.null;
                }

                var is_safe = false;

                for (node.variable.?.filters) |f| {
                    const filter_fn = builtin_filters.get(f.name) orelse return error.UnknownFilter;

                    // const arg = if (f.arg) |a| Value{ .string = a } else null;
                    var arg: Value = Value.null;
                    if (f.arg) |a| {
                        arg = Value{ .string = a };
                        const result = try std.fmt.parseInt(i64, a, 10);
                        if (std.math.maxInt(i64) < result) return error.Overflow;
                        arg = Value{ .int = result };
                    }
                    value = try filter_fn(alloc, value, arg);

                    if (std.mem.eql(u8, f.name, "safe")) is_safe = true;
                }

                if (!is_safe) {
                    if (builtin_filters.get("escape")) |escape_fn| {
                        value = try escape_fn(alloc, value, null);
                    }
                }

                var buf = ArrayListUnmanaged(u8){};
                defer buf.deinit(alloc);

                try self.valueToString(alloc, &buf, value);
                try writer.writeAll(buf.items);
            },
            .if_block => {
                const condition = self.evaluateCondition(node.@"if".?.condition) catch return false;

                if (condition) {
                    for (node.@"if".?.true_body) |child| {
                        try self.renderNode(alloc, nodes, child, writer, null, null);
                    }
                } else {
                    for (node.@"if".?.false_body) |child| {
                        try self.renderNode(alloc, nodes, child, writer, null, null);
                    }
                }
            },
            .include => {
                const included_template = try self.readTemplateFile(node.include.?.template_name);
                defer alloc.free(included_template);

                var included_parser = parser.Parser.init(included_template);
                const included_nodes = try included_parser.parse(alloc);
                defer {
                    for (included_nodes) |n| n.deinit(alloc);
                    alloc.free(included_nodes);
                }

                // Renderiza o include no contexto atual (sem novo contexto)
                for (included_nodes) |included_node| {
                    try self.renderNode(alloc, nodes, included_node, writer, context, null);
                }
            },
            .for_block => {
                const list_value = self.context.get(node.@"for".?.iterable) orelse Value.null;
                const list = switch (list_value) {
                    .list => |l| l,
                    else => return,
                };

                for (list) |item| {
                    var ctx = Context.init(alloc);
                    defer ctx.deinit();

                    try ctx.set(node.@"for".?.loop_var, item);

                    for (node.@"for".?.body) |child| {
                        try self.renderNode(alloc, nodes, child, writer, &ctx, null);
                    }

                    for (node.@"for".?.empty_body) |child| {
                        try self.renderNode(alloc, nodes, child, writer, &ctx, null);
                    }
                }
            },
            .super => {
                if (parent_block_nodes) |parent| {
                    for (parent) |child| {
                        try self.renderNode(alloc, nodes, child, writer, null, null);
                    }
                }
            },
            .block => {
                for (node.block.?.body) |child| {
                    const parent_content = parent_block_nodes orelse node.block.?.body;
                    try self.renderNode(alloc, nodes, child, writer, null, parent_content);
                }
            },
            else => {},
        }
    }

    fn findChildBlock(self: *const Renderer, nodes: []parser.Node, name: []const u8) ?parser.BlockNode {
        _ = self;
        for (nodes) |n| {
            if (n.type != .block) continue;
            if (std.mem.eql(u8, n.block.?.name, name)) return n.block.?;
        }
        return null;
    }

    fn valueToString(self: *const Renderer, alloc: Allocator, buf: *ArrayListUnmanaged(u8), value: Value) !void {
        _ = self;
        var w = buf.writer(alloc);
        switch (value) {
            .null => try w.writeAll("null"),
            .bool => |b| try w.print("{}", .{b}),
            .int => |n| try w.print("{d}", .{n}),
            .float => |f| try w.print("{d}", .{f}),
            .string => |s| try w.writeAll(s),
            .list => try w.writeAll("[list]"),
            .dict => try w.writeAll("{dict}"),
        }
    }

    fn evaluateCondition(self: *const Renderer, expr: []const u8) !bool {
        const value = self.context.get(expr) orelse Value.null;
        return switch (value) {
            .bool => |b| b,
            .int => |i| i != 0,
            .float => |f| f != 0.0,
            .string => |s| s.len > 0,
            .list => |l| l.len > 0,
            .dict => |d| d.count() > 0,
            .null => false,
        };
    }

    fn evaluateCondition(self: *const Renderer, allocator: Allocator, expr: []const u8) RenderError!bool {
        const trimmed = std.mem.trim(u8, expr, " \t\r\n");
        if (trimmed.len == 0) return false;

        var parts = std.mem.splitScalar(u8, trimmed, ' ');

        // Coleta tokens não vazios
        var tokens = std.ArrayList([]const u8){};
        defer tokens.deinit(allocator);

        while (parts.next()) |part| {
            const t = std.mem.trim(u8, part, " \t\r\n");
            if (t.len > 0) try tokens.append(allocator, t);
        }

        // Caso simples: só nome de variável
        if (tokens.items.len == 1) {
            const value = self.context.get(tokens.items[0]) orelse Value.null;
            return isTruthy(value);
        }

        // Caso especial: "not variavel"
        if (tokens.items.len == 2 and std.mem.eql(u8, tokens.items[0], "not")) {
            const value = self.context.get(tokens.items[1]) orelse Value.null;
            return !isTruthy(value);
        }

        // Caso com operadores de comparação: var op valor
        if (tokens.items.len == 3) {
            const left = tokens.items[0];
            const op = tokens.items[1];
            const right_str = tokens.items[2];

            const left_value = self.context.get(left) orelse Value.null;
            const right_value = parseLiteral(right_str);

            if (std.mem.eql(u8, op, ">")) return compare(left_value, right_value, .gt);
            if (std.mem.eql(u8, op, "<")) return compare(left_value, right_value, .lt);
            if (std.mem.eql(u8, op, ">=")) return compare(left_value, right_value, .ge);
            if (std.mem.eql(u8, op, "<=")) return compare(left_value, right_value, .le);
            if (std.mem.eql(u8, op, "==")) return compare(left_value, right_value, .eq);
            if (std.mem.eql(u8, op, "!=")) return compare(left_value, right_value, .ne);

            return error.InvalidSyntax;
        }

        // Caso mais complexo (and/or/not composto) - por enquanto erro
        return error.UnsupportedExpression;
    }

    // Função auxiliar: converte string literal pra Value
    fn parseLiteral(str: []const u8) Value {
        const trimmed = std.mem.trim(u8, str, " \t\r\n\"'");
        if (std.mem.eql(u8, trimmed, "true")) return Value{ .bool = true };
        if (std.mem.eql(u8, trimmed, "false")) return Value{ .bool = false };
        if (std.mem.eql(u8, trimmed, "null")) return Value.null;

        if (std.fmt.parseInt(i64, trimmed, 10)) |n| return Value{ .int = n } else |_| {}
        if (std.fmt.parseFloat(f64, trimmed)) |f| return Value{ .float = f } else |_| {}

        return Value{ .string = trimmed };
    }

    // Função auxiliar: truthy check
    fn isTruthy(v: Value) bool {
        return switch (v) {
            .null => false,
            .bool => |b| b,
            .int => |i| i != 0,
            .float => |f| f != 0.0,
            .string => |s| s.len > 0,
            .list => |l| l.len > 0,
            .dict => |d| d.count() > 0,
        };
    }

    // Função auxiliar: comparação
    fn compare(left: Value, right: Value, op: enum { gt, lt, ge, le, eq, ne, not }) bool {
        // Implementação básica (expanda conforme necessário)
        switch (left) {
            .int => |l| switch (right) {
                .int => |r| return switch (op) {
                    .gt => l > r,
                    .lt => l < r,
                    .ge => l >= r,
                    .le => l <= r,
                    .eq => l == r,
                    .ne, .not => l != r,
                },
                else => return false,
            },
            .float => |l| switch (right) {
                .float => |r| return switch (op) {
                    .gt => l > r,
                    .lt => l < r,
                    .ge => l >= r,
                    .le => l <= r,
                    .eq => l == r,
                    .ne, .not => l != r,
                },
                else => return false,
            },
            .string => |l| switch (right) {
                .string => |r| return switch (op) {
                    .eq => std.mem.eql(u8, l, r),
                    .ne, .not => !std.mem.eql(u8, l, r),
                    else => false,
                },
                else => return false,
            },
            else => return false,
        }
    }
};