// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include "util/mustache/mustache.h"

#include <rapidjson/allocators.h>

#include <rapidjson/document.h>

#include <rapidjson/encodings.h>

#include <rapidjson/prettywriter.h>

#include <rapidjson/rapidjson.h>

#include <strings.h>

#include <algorithm>

#include <boost/algorithm/string/classification.hpp>

#include <boost/algorithm/string/detail/classification.hpp>

#include <boost/algorithm/string/join.hpp>

#include <boost/algorithm/string/predicate_facade.hpp>

#include <boost/algorithm/string/split.hpp>

#include <boost/algorithm/string/trim.hpp>

#include <boost/iterator/iterator_facade.hpp>

#include <boost/type_index/type_index_facade.hpp>

#include <fstream> // IWYU pragma: keep

#include <iostream>

#include <stack>

#include <vector>

#include "rapidjson/stringbuffer.h"

#include "rapidjson/writer.h"

using namespace rapidjson;

using namespace boost::algorithm;

namespace mustache {

// TODO:

// # Handle malformed templates better

// # Better support for reading templates from files

enum TagOperator {

    SUBSTITUTION,

    SECTION_START,

    NEGATED_SECTION_START,

    PREDICATE_SECTION_START,

    SECTION_END,

    PARTIAL,

    COMMENT,

    LENGTH,

    EQUALITY,

    INEQUALITY,

    LITERAL,

    NONE

};

struct OpCtx {

    TagOperator op;

    std::string tag_name;

    std::string tag_arg;

    bool escaped = false;

};

struct ContextStack {

    const Value* value;

    const ContextStack* parent;

};

TagOperator GetOperator(const std::string& tag) {

    if (tag.size() == 0) return SUBSTITUTION;

    switch (tag[0]) {

    case '#':

        return SECTION_START;

    case '^':

        return NEGATED_SECTION_START;

    case '?':

        return PREDICATE_SECTION_START;

    case '/':

        return SECTION_END;

    case '>':

        return PARTIAL;

    case '!':

        if (tag.size() == 1 || tag[1] != '=') return COMMENT;

        return INEQUALITY;

    case '%':

        return LENGTH;

    case '~':

        return LITERAL;

    case '=':

        return EQUALITY;

    default:

        return SUBSTITUTION;

    }

}

int EvaluateTag(const std::string& document, const std::string& document_root, int idx,

                const ContextStack* context, const OpCtx& op_ctx, std::stringstream* out);

static bool RenderTemplate(const std::string& document, const std::string& document_root,

                           const ContextStack* stack, std::stringstream* out);

void EscapeHtml(const std::string& in, std::stringstream* out) {

    for (const char& c : in) {

        switch (c) {

        case '&':

            (*out) << "&amp;";

            break;

        case '"':

            (*out) << "&quot;";

            break;

        case '\'':

            (*out) << "&apos;";

            break;

        case '<':

            (*out) << "&lt;";

            break;

        case '>':

            (*out) << "&gt;";

            break;

        default:

            (*out) << c;

            break;

        }

    }

}

void Dump(const rapidjson::Value& v) {

    StringBuffer buffer;

    Writer<StringBuffer> writer(buffer);

    v.Accept(writer);

    std::cout << buffer.GetString() << std::endl;

}

// Breaks a dotted path into individual components. One wrinkle, which stops this from

// being a simple split() is that we allow path components to be quoted, e.g.: "foo".bar,

// and any '.' characters inside those quoted sections aren't considered to be

// delimiters. This is to allow Json keys that contain periods.

void FindJsonPathComponents(const std::string& path, std::vector<std::string>* components) {

    bool in_quote = false;

    bool escape_this_char = false;

    int start = 0;

    for (int i = start; i < path.size(); ++i) {

        if (path[i] == '"' && !escape_this_char) in_quote = !in_quote;

        if (path[i] == '.' && !escape_this_char && !in_quote) {

            // Current char == delimiter and not escaped and not in a quote pair => found a

            // component

            if (i - start > 0) {

                if (path[start] == '"' && path[(i - 1) - start] == '"') {

                    if (i - start > 3) {

                        components->push_back(path.substr(start + 1, i - (start + 2)));

                    }

                } else {

                    components->push_back(path.substr(start, i - start));

                }

                start = i + 1;

            }

        }

        escape_this_char = (path[i] == '\\' && !escape_this_char);

    }

    if (path.size() - start > 0) {

        if (path[start] == '"' && path[(path.size() - 1) - start] == '"') {

            if (path.size() - start > 3) {

                components->push_back(path.substr(start + 1, path.size() - (start + 2)));

            }

        } else {

            components->push_back(path.substr(start, path.size() - start));

        }

    }

}

// Looks up the json entity at 'path' in 'parent_context', and places it in 'resolved'. If

// the entity does not exist (i.e. the path is invalid), 'resolved' will be set to nullptr.

void ResolveJsonContext(const std::string& path, const ContextStack* stack,

                        const Value** resolved) {

    if (path == ".") {

        *resolved = stack->value;

        return;

    }

    std::vector<std::string> components;

    FindJsonPathComponents(path, &components);

    // At each enclosing level of context, try to resolve the path.

    for (; stack != nullptr; stack = stack->parent) {

        const Value* cur = stack->value;

        bool match = true;

        for (const std::string& c : components) {

            if (cur->IsObject() && cur->HasMember(c.c_str())) {

                cur = &(*cur)[c.c_str()];

            } else {

                match = false;

                break;

            }

        }

        if (match) {

            *resolved = cur;

            return;

        }

    }

    *resolved = nullptr;

}

int FindNextTag(const std::string& document, int idx, OpCtx* op, std::stringstream* out) {

    op->op = NONE;

    while (idx < document.size()) {

        if (document[idx] == '{' && idx < (document.size() - 3) && document[idx + 1] == '{') {

            if (document[idx + 2] == '{') {

                idx += 3;

                op->escaped = true;

            } else {

                op->escaped = false;

                idx += 2; // Now at start of template expression

            }

            std::stringstream expr;

            while (idx < document.size()) {

                if (document[idx] != '}') {

                    expr << document[idx];

                    ++idx;

                } else {

                    if (!op->escaped && idx < document.size() - 1 && document[idx + 1] == '}') {

                        ++idx;

                        break;

                    } else if (op->escaped && idx < document.size() - 2 &&

                               document[idx + 1] == '}' && document[idx + 2] == '}') {

                        idx += 2;

                        break;

                    } else {

                        expr << '}';

                    }

                }

            }

            std::string key = expr.str();

            trim(key);

            if (key != ".") trim_if(key, is_any_of("."));

            if (key.size() == 0) continue;

            op->op = GetOperator(key);

            if (op->op != SUBSTITUTION) {

                int len = op->op == INEQUALITY ? 2 : 1;

                key = key.substr(len);

                trim(key);

            }

            if (key.size() == 0) continue;

            if (op->op == EQUALITY || op->op == INEQUALITY) {

                // Find an argument

                std::vector<std::string> components;

                split(components, key, is_any_of(" "));

                key = components[0];

                components.erase(components.begin());

                op->tag_arg = join(components, " ");

            }

            op->tag_name = key;

            return ++idx;

        } else {

            if (out != nullptr) (*out) << document[idx];

        }

        ++idx;

    }

    return idx;

}

// Evaluates a [PREDICATE_|NEGATED_]SECTION_START / SECTION_END pair by evaluating the tag

// in 'parent_context'. False or non-existant values cause the entire section to be

// skipped. True values cause the section to be evaluated as though it were a normal

// section, but with the parent context being the root context for that section.

//

// If 'is_negation' is true, the behaviour is the opposite of the above: false values

// cause the section to be normally evaluated etc.

int EvaluateSection(const std::string& document, const std::string& document_root, int idx,

                    const ContextStack* context_stack, const OpCtx& op_ctx,

                    std::stringstream* out) {

    // Precondition: idx is the immediate next character after an opening {{ #tag_name }}

    const Value* context;

    ResolveJsonContext(op_ctx.tag_name, context_stack, &context);

    // If we a) cannot resolve the context from the tag name or b) the context evaluates to

    // false, we should skip the contents of the template until a closing {{/tag_name}}.

    bool skip_contents = false;

    if (op_ctx.op == NEGATED_SECTION_START || op_ctx.op == PREDICATE_SECTION_START ||

        op_ctx.op == SECTION_START) {

        skip_contents = (context == nullptr || context->IsFalse());

        // If the tag is a negative block (i.e. {{^tag_name}}), do the opposite: if the

        // context exists and is true, skip the contents, else echo them.

        if (op_ctx.op == NEGATED_SECTION_START) {

            context = context_stack->value;

            skip_contents = !skip_contents;

        } else if (op_ctx.op == PREDICATE_SECTION_START) {

            context = context_stack->value;

        }

    } else if (op_ctx.op == INEQUALITY || op_ctx.op == EQUALITY) {

        skip_contents = (context == nullptr || !context->IsString() ||

                         strcasecmp(context->GetString(), op_ctx.tag_arg.c_str()) != 0);

        if (op_ctx.op == INEQUALITY) skip_contents = !skip_contents;

        context = context_stack->value;

    }

    std::vector<const Value*> values;

    if (!skip_contents && context != nullptr && context->IsArray()) {

        for (int i = 0; i < context->Size(); ++i) {

            values.push_back(&(*context)[i]);

        }

    } else {

        values.push_back(skip_contents ? nullptr : context);

    }

    if (values.size() == 0) {

        skip_contents = true;

        values.push_back(nullptr);

    }

    int start_idx = idx;

    for (const Value* v : values) {

        idx = start_idx;

        std::stack<OpCtx> section_starts;

        section_starts.push(op_ctx);

        while (idx < document.size()) {

            OpCtx next_ctx;

            idx = FindNextTag(document, idx, &next_ctx, skip_contents ? nullptr : out);

            if (skip_contents &&

                (next_ctx.op == SECTION_START || next_ctx.op == PREDICATE_SECTION_START ||

                 next_ctx.op == NEGATED_SECTION_START)) {

                section_starts.push(next_ctx);

            } else if (next_ctx.op == SECTION_END) {

                if (next_ctx.tag_name != section_starts.top().tag_name) return -1;

                section_starts.pop();

            }

            if (section_starts.empty()) break;

            // Don't need to evaluate any templates if we're skipping the contents

            if (!skip_contents) {

                ContextStack new_context = {v, context_stack};

                idx = EvaluateTag(document, document_root, idx, &new_context, next_ctx, out);

            }

        }

    }

    return idx;

}

// Evaluates a SUBSTITUTION tag, by replacing its contents with the value of the tag's

// name in 'parent_context'.

int EvaluateSubstitution(const std::string& document, const int idx,

                         const ContextStack* context_stack, const OpCtx& op_ctx,

                         std::stringstream* out) {

    const Value* val;

    ResolveJsonContext(op_ctx.tag_name, context_stack, &val);

    if (val == nullptr) return idx;

    if (val->IsString()) {

        if (!op_ctx.escaped) {

            EscapeHtml(val->GetString(), out);

        } else {

            // TODO: Triple {{{ means don't escape

            (*out) << val->GetString();

        }

    } else if (val->IsInt64()) {

        (*out) << val->GetInt64();

    } else if (val->IsInt()) {

        (*out) << val->GetInt();

    } else if (val->IsDouble()) {

        (*out) << val->GetDouble();

    } else if (val->IsBool()) {

        (*out) << std::boolalpha << val->GetBool();

    }

    return idx;

}

// Evaluates a LENGTH tag by replacing its contents with the type-dependent 'size' of the

// value.

int EvaluateLength(const std::string& document, const int idx, const ContextStack* context_stack,

                   const std::string& tag_name, std::stringstream* out) {

    const Value* val;

    ResolveJsonContext(tag_name, context_stack, &val);

    if (val == nullptr) return idx;

    if (val->IsArray()) {

        (*out) << val->Size();

    } else if (val->IsString()) {

        (*out) << val->GetStringLength();

    };

    return idx;

}

int EvaluateLiteral(const std::string& document, const int idx, const ContextStack* context_stack,

                    const std::string& tag_name, std::stringstream* out) {

    const Value* val;

    ResolveJsonContext(tag_name, context_stack, &val);

    if (val == nullptr) return idx;

    if (!val->IsArray() && !val->IsObject()) return idx;

    StringBuffer strbuf;

    PrettyWriter<StringBuffer> writer(strbuf);

    val->Accept(writer);

    (*out) << strbuf.GetString();

    return idx;

}

// Evaluates a 'partial' template by reading it fully from disk, then rendering it

// directly into the current output with the current context.

//

// TODO: This could obviously be more efficient (and there are lots of file accesses in a

// long list context).

void EvaluatePartial(const std::string& tag_name, const std::string& document_root,

                     const ContextStack* stack, std::stringstream* out) {

    std::stringstream ss;

    ss << document_root << tag_name;

    std::ifstream tmpl(ss.str().c_str());

    if (!tmpl.is_open()) {

        ss << ".mustache";

        tmpl.open(ss.str().c_str());

        if (!tmpl.is_open()) return;

    }

    std::stringstream file_ss;

    file_ss << tmpl.rdbuf();

    RenderTemplate(file_ss.str(), document_root, stack, out);

}

// Given a tag name, and its operator, evaluate the tag in the given context and write the

// output to 'out'. The heavy-lifting is delegated to specific Evaluate*()

// methods. Returns the new cursor position within 'document', or -1 on error.

int EvaluateTag(const std::string& document, const std::string& document_root, int idx,

                const ContextStack* context, const OpCtx& op_ctx, std::stringstream* out) {

    if (idx == -1) return idx;

    switch (op_ctx.op) {

    case SECTION_START:

    case PREDICATE_SECTION_START:

    case NEGATED_SECTION_START:

    case EQUALITY:

    case INEQUALITY:

        return EvaluateSection(document, document_root, idx, context, op_ctx, out);

    case SUBSTITUTION:

        return EvaluateSubstitution(document, idx, context, op_ctx, out);

    case COMMENT:

        return idx; // Ignored

    case PARTIAL:

        EvaluatePartial(op_ctx.tag_name, document_root, context, out);

        return idx;

    case LENGTH:

        return EvaluateLength(document, idx, context, op_ctx.tag_name, out);

    case LITERAL:

        return EvaluateLiteral(document, idx, context, op_ctx.tag_name, out);

    case NONE:

        return idx; // No tag was found

    case SECTION_END:

        return idx;

    default:

        std::cout << "Unknown tag: " << op_ctx.op << std::endl;

        return -1;

    }

}

static bool RenderTemplate(const std::string& document, const std::string& document_root,

                           const ContextStack* stack, std::stringstream* out) {

    int idx = 0;

    while (idx < document.size() && idx != -1) {

        OpCtx op;

        idx = FindNextTag(document, idx, &op, out);

        idx = EvaluateTag(document, document_root, idx, stack, op, out);

    }

    return idx != -1;

}

bool RenderTemplate(const std::string& document, const std::string& document_root,

                    const Value& context, std::stringstream* out) {

    ContextStack stack = {&context, nullptr};

    return RenderTemplate(document, document_root, &stack, out);

}

} // namespace mustache